First of all, I think you're overestimating Novak quite a bit (understandable as a fan of his, but nevertheless. I'm a fan too - he's just not my no. 1 favorite). We haven't seen Novak win multiple slams a year anywhere else than in 2011 and yet you have him do it year after year after year.
To me, Novak has been the best player since 2011, but he hasn't capitalized sufficiently on it, because he just hasn't been able to bring his best level in multiple of the slams (especially finals) he's lost. For whatever mental or physical reason. That didn't happen to peak Fed.
Anyhow, I'll go with you on the points below.
I've explained this point before, there #s he has continuing from 09-12 show that he was still performing at a high level throughout that period. I can concede 08 was a "valley" year for Fed, but not that it was "out of his prime Fed" the way some of his fans want to portray. That is what I mean about the decline. People want to say 11/16 slams in 04-07 followed by 4/12 is fully attributable to a hard decline.
Without mono, I would have expected Fed's reign to last a bit longer. I know this is a controversial point, but 2008 was more than a valley - it was a pretty deep valley and what happened in that valley affected his confidence going forward.
I'm not sure Fed would have lost the 08 Wimbledon final had the beatdown at RG not happened.
And I'm not sure he would have lost AO 09 had the 2008 beatings not happened as his mental state wasn't half as bad vs. Rafa in 2007 for instance.
And I'm also not sure he would have lost AO 2008 had he not been severely affected by mono.
Would he have won all of them? Perhaps not. But it certainly took it's toll on him.
All in all, the 4/12 is a mixture of the rest of the Big 4, in particular Rafa, getting better and Fed declining (losing to the Sod and Berdych in 2010 can certainly be attributed to age-related decline).
I acknowledge the over-all levels might have been similar, but I am talking about the competition at the top (the guys who can fight you off for titles regularly). I'm saying Novak lost more slams in winning positions than Fed has. Take a look at some of his slam finals loses off clay: Fed, Murray, Murray, Nadal, Nadal. I would take a stronger depth field headlined by Baghdatis or Gonzales or Hewitt or Roddick or 35-Y/O Agassi vs those and expect Nole to come away with many of those titles.
Again - as I wrote initially - we really don't know that Novak has the right mental approach to stay on top week after week after week. Lendl had, Sampras had, Fed had. But those are the only ones since Borg if I'm not mistaken.
I've posted the fields Fed went through in 04-07 - I don't think Novak would have walzed through them, certainly not on grass and also not quite at the US.
But overall, I do concede that Novak would have done (slightly) better had he been born in 81.
Two points here. 1) Not saying he would have lost many, but certainly more than 1 off clay in 4 years at slams. 2) The comparison isn't about Nole and Fed in the same era, its if Nole was placed into his 20 year old form in 01 (as Fed had) and Fed was moved to his 20 year old for coming in 07.
Well, that's your comparison. I made another

Anyhow, probably more than 1 yes - but I also think he would be the one of the Big 4 doing better in his 30's if all of them were the same age given how relatively competitive he's been able to stay and given that he relies more on his serve and less on incredible defense. So in that sense, losing a couple more in his peakest peak would be outbalanced by being able to feast on the 2010/11-15 years, where - I presume - Rafa, Djoker and Murray would have declined more than Fed and no other serious slam contesters were present.
I would agree with you on Wimbledon and the French, but I think you underrate Novak on the hard courts. I would favor them as such:
Wimb: 75/25 Fed
FO: 50/50
USO: 55/45 Fed
AO: 66/33 Novak
Keep in mind Rebound is still a slow hard court. It merely bounces less, this doesn't hurt Novak as much as it hurt Rafa.
I'd take Fed as the favorite on all courts over Murray too, but Murray would take a slam match I'd wager as opposed to Roddick/Hewitt who never did. As you allude to, I also think prime Novak could have been a nightmare for pre-prime Rafa and even likely won that early 05 French.
I actually alluded to Rafa being a nightmare for Fed (but as I also said, even that may be a bit different if they were the same age) - but the point may be true about Novak-Rafa too though it's hard to imagine how their match-up would have been, had Novak been first out of the gate.
Murray would be tough in some matches, but I wouldn't take Murray over Fed in a slam at the same age. Fed held him off until AO 2013, where he was 31,5 years old and still took him to 5. I just don't see it, but I won't outrule it.
We have different percentages (no surprise there). I think you underestimate Fed on HC. No doubt they've been the two best HC players since Sampras and Agassi though:
Wimb: 80/20 Fed (I just think Fed is a vastly better grass-courter than Novak)
FO: 50/50
USO: 65/35 Fed (if old Fed can take peak Novak to MP twice, I would bet my money on peak Fed vs. peak Novak)
AO: 55-60/40-45, Novak (11 semis in a row ain't that shabby - and I recall Rebound as more of medium)
Fair points and I guess something we will never know, but just to run through a hypothetical with you this is what I foresee happening if you moved Roger and Novak's careers.
Novak - from 07-09 he was a force at USO only losing to prime Fed/Nadal and dropping another AO to Fed and two other FO to Nadal (both in SF, one against pure peak clay Nadal) plus the AO he won. This was all done at ages younger than Fed's 04.
From 01-03 I see Nole as a contender for the AO, USO, FO every year. I think he is favored for 1 at each court and a contender for 1 more. 3-4 slams.
I think the above is being too generous.
AO 2001, too young.
FO 2001, don't think he beats Gustavo
US 2001, wouldn't favor him vs. Hewitt, Pete, Agassi, Roddick etc. Contender sure. Favorite, no.
AO 02 - yes, that one he gets.
FO 02, decent to good chance
US 02, would favor Pete's last hurray, Novak doesn't like serves that big + Pete also had quite a bit of game to go with it.
AO 03, nah - he retired vs. Roddick in 09 and was pushed a lot before that.
FO 2003 - lost to Kohlschreiber in 09.
US 03, that's probably his best chance aside from the AO 02. But I wouldn't just give it to him - Roddick leads the h2h and this was Roddick at his best.
2004 - equal to his 2010, where he was a mess up until the US Open (AO, Tsonga, FO, Melzer), where he beat his first top-10 player that year! At most a US Open that year and that's being a little bit generous.
All in all, I wouldn't give him more than 2-3 slams in this period, prop. max. 3.
(AO 2002, yes. FO 2002, quite likely. US 04, quite likely. US 03, best chance for a 4th).
But in these scenarios, it's completely possible that he would also simply just recognize the window of opportunity and not have his 09-10 slump - or do even worse as he was the top dog from an early age. We just don't know.
From 04-07 in his prime years: 04 is 10, which I've counted above - not a prime year by any standards imo
3-4 AO fav (04, 06, 07, contender vs Safin in 05)
1-2 FO (04, possible win in 05, losses to Rafa 06/07)
2-3 Wimb (1 of 2 vs Roddick in 04/05, 06, possible win in 07 vs Nadal)
2-3 USO (someone of the Hewitt/Roddick/Safin crew would take 1 at least, and might lose another)
total = 8-12 majors + 3-4 before = 11-16 by 07
2005, AO, possibly FO, possibly Wim (could see him lose to both Hewitt and Roddick), US. Though a max of 3. There's a reason why no one wins all 4.
3 slams
2006, AO, no FO, possibly Wim, possibly US, but no certainty.
1-3 slams.
2007, AO, likely but by no means certain (again, Gonzalez was damn good that year). No FO, no Wimbledon. Possibly US.
0-2 slams.
2008: AO (it's getting tricky), but no. No FO. Possibly Wimbledon (we can't just assume Novak would be in his Rafa beating-mode as I did elsewhere in this thread as in this scenario, his career would progress ahead of Rafa's.)
0-1 slams so far.
The rest is in the future, so I won't go into detail with that as we don't know how Novak will age yet.
All in all:
2-3 + 3 + 1-3 + 0-2 + 0-1 = 6-12 slams with around 8-9 being the most likely imo.
Where Fed had 12 at this point.
Let this be said though - as much as Fedal has hurt him by winning some slams against him as much has their standards helped Novak become the player he is. There is simply no way of knowing (but I tend to go with no) that Novak would be as good a player as he is had he not had Fed and Rafa to surpass.
Same with Rafa who had Fed to take some of the pressure of him (I seriously doubt that Rafa would have dealt well with being the hunted at the age of 19).
This took a while....
Despite me believing there are fundamentally too many intangibles to consider. Would Djoko even have his two-hander had he been born six years earlier? Would he have experienced war or had a more fortunate upbringing and what would that have done to his fighter mentality? Would he ever have met his childhood coach? Would he have been able to keep himself motivated as a clear world no. 1?
Etc.
But the above is looking beyond those things and just trying to go year by year - even though I really don't believe in that approach as I doubt the Novak in 2005-2008 would have been as good as the one who turned up in 2011-2014 - partly courtesy of having to go through Fedal to get his own spot in the sunshine and courtesy of watching how they went about their business.