Played Baseball 25 years everyday or else I would be using Full Poly string bed. However, even soft Poly strings like Sonic Pro Edge and others make my shoulder bark. I plan on playing tennis a long time so I am trying to think long term about my arm health. I have to say, the Monogut ZX hits the mark for me in almost all categories. It doesnt hurt my arm but I can shape the ball and "hit out" because of the control I get and spin. Its almost full poly like in the way I can control it. I do prefer the "touch" and less "plasticky" feel of PPA and Natural Gut at the net but that's not enough considering the other positives. Bottom LIne..No arm issues-poly like spin..