pc1, I understand where you're coming from and I do respect you point of view, however I have repeated ad nauseum the fact that you can't use age as a relativistic standard to compare progress rates and achievments accrued by individuals (upto a certain arbitrary end-point in time) whose tennis careers have developed quite differently from one another. By that token, had you compared them a couple of years ago, Nadal would have had an even better success rate vis-a-vis Federer at a similar age.
Federer was not as precocious and early a bloomer as Nadal. Federer come in into his own at the of 21 and if you take a gander at his statistical resume from thereonin until the end of his prime in 2007, his rate of his success accrual has no precedent in the Open Era. Nadal in comparision has thus far accumulated his titled at a relatively more steady rate and never had as appreciable an incline as Federer did over the 4 years he dominated the tour. Federer won his first major in 2003 -- from 2003 to 2007 he won 12 majors in 4 years.
If anything, Nadals success rate has decreased with age compared to Federer's) such that now they appear relatively even, and if trends are anything to go buy the chances are that it will fall further. Hence, provided my last statement proves true, were you to compare them again by using the same criteria in the future, the result would more than likely be in Federer's favor. This is the fallacy of using this criteria as a determinant to compare the success of individuals at a similar age. At this point, as I have said before Federer is the far greater player. However, let's wait for both of them to retire before we can "more objectively" determine their stature relative to one another.
P.S I agree that my statement of "Federer being the most successful player in history" should should be contexualized within the scope of the Open Era. The rest of your post I do not agree. Any "objectivity" that utilizes any sembelance of cognitive relativism to justify its existence, is... not objective.