Originally Posted by tlm
Poly does not do everything better. Poly can never compare to the consistent control of kevlar, never especially after a few hours or days. Pro players change their string jobs every ball change which is around a half hour or so.
So us amateur players that use a string job for much longer will not enjoy the magic of poly that only lasts for a hour or two.
This is not a general rule. Federer does this, every 6 games I believe. Venus Williams has on many occasions played with a single racquet per match when winning. This was when she played full gut, and now when playing a poly hybrid.
There is already a thread on this topic actually. For a high swing speed, poly will return more energy into the ball in the form of spin than Kevlar. As I mentioned in that thread, Agassi who used Kevlar for many many years said something to the effect that they need to let everyone know about poly or get rid of it because it produces so much spin per stroke. Sampras, upon trying it in retirement, said that it was like cheating due to the shots he could hit. Jim Courier at first didn't like poly BECAUSE it produced too much spin and he couldn't hit flat enough.
Regardless, if you feel Kevlar produces more spin, then use Kevlar. The likely reason you are getting the impression of greater spin is because Kevlar lets you swing as hard as you want at the ball, more or less. Poly, on the other hand, has more power, but greater elasticity, so if you have a less spin-generating stroke, then your impression will be that Kevlar is better for spin. I'm not going to argue why an entire industry has shifted if you personally like the spin of Kevlar.