It looks like using full poly is improving my game. When playing with softer strings, including syngut and multis, I remember I used to "cheat" a lot more on my strokes, often opting to just punch the ball back, especially in tight spots. With poly, short and lazy strokes just don't have any pace or control, feel harsh, and cause a lot of errors. Also, when I tense up my arm, the impact is very uncomfortable, so I am forced to loosen my grip more and to swing more freely, rather than forcing the racket through the ball. All this is improving my game. It seems that poly strings provide a lot more feedback when you do something wrong. For a developing player, perhaps at 3.5 and below, who mishits often, I think you definitely risk injury, although you still get the benefit of getting good feedback. However, if you're almost there, in terms of having a full/fast stroke and being able to hit the sweet spot often, it seems like an great learning aide, plus you get lots of spin and control. Have you had a similar experience?