I've seen kids hit with the light balls and it looks like a lot of fun. But in terms of laerning to hit hard and flat, I'm not sure it's the best form of practice. I look at the dominance of players born in 81, 85 and 87, they look to be right on the cusp between the graphite/gut era and the Babolat/poly era.
dude, look where Roddick, Hewitt, Safin, Nalbandian, Davydenko, and almost every other pro player born in the beginning of the 80s are.
they mostly retired. It's Fed and Karlovic from those years.
Heck, even the Djokodal generation is having troubles.
Berdych retired.
Age is catching up with Wawrinka and Murray, and while kudos to them for still trying, they will probably not come back to top 10 anymore.
If Sampras didn't retire after winning the USO 2002, for another 12 months he would be a top 20 player on those USO 2002 points alone, but he did retire.
Dimitrov who is 29 years old is seeing his results fading down because of injuries.
If there is one conclusion that you can make out of the Big 3 domination, that:
Fed and Novak were able to avoid major career threatening injuries, with Novak being very lucky with his elbow injury being healed, or managed
Nadal is a truly unique athlete, coming back after so many injuries, in particular on knees.
it's not really about rackets used in childhood.
it's much more about extending the years when your footwork allows you to be competitive.
Do you remeber Janko Tipsarevic? born in 1984, he was famous for his footwork, but injuries had something to say.