Glad to see this thread come back. It's timely for me since I partially tore an elbow ligament during last USTA season and had to finish out with that injury. Got my a** handed to me a few times, but after that I took 3 months off and recovered.
To get through that season I played with a weighted up APD strung with very low tension poly. SW was around 335 or so. I started with gut and multi in the 50's, but the 40#s low tension poly was easier on my arm. This was because I realized I had been back to swinging too hard and trying to flatten out the ball with more old school frames. It just doesn't work for me.
Anyway after I got better I grabbed some Rafa Origins since they were on a deep sale. Did not expect to really use them that much, but it's all I have been using since. Been working with a coach who runs me ragged and has me fine tuning the kinetic chain on groundies and serve. I am back to 355-360 SW and it's been going great so far. Will see how it evolves over the next few months. The high SW is probably the one racquet change that makes the most impact on the court. People notice when the ball is coming at them with that extra weight behind it, because I get comments like "wtf man, I thought your arm was injured".
I think up to 4.5, probably even to 5.0 and under, you can use this type of setup as long as you are committed to technical improvement. Arming the ball is not going to work. I think this is good for a lot of players like me who tend to over swing and abandon the kinetic chain sometimes in the heat of battle. The higher SW just keeps me relaxed and focused on my movement, because I dont need to do much above the waist.
Above 5.0 the game is going to be at another level of speed and I see why pros are dropping their SW into the 330s now. It's also why so many college players use stock frames. Why not, the ball is coming at you with heat. When the average ball is coming at you with serious pace, you don't need as much SW to generate a big shot, especially with good hand eye. But at normal rec level, there are just not a lot of players that are going to give that type of pace shot after shot. The best 4.0s in my area are patient and don't really hit hard unless they have a clear winner. It's more about placement over pace, staying relaxed, hitting deep and moving well.