Yes, I love Racquet and string technology and all things tennis geek. For about a year I've been settled on gut mains and poly crosses and love that approach. I've also stuck with the 300 for several months and really enjoy it. Mostly I've been working on my serve and can see huge improvement. Starting to focus on return of serve against friends who serve big. But being a tennis tech geek I can't help but fool around with different frames and strings. Today I demoed a YouTek IG Radical Pro with fully poly. the Radical Pro is in the low to mid 60s stiffness wise. The poly was supposedly a soft copoly (Scorpion maybe?). Hit some serves and the wall and OUCH! After a little while I could feel pain in my arm and soon stopped. Later in the afternoon the pain increased. I truly have a whimpy arm. I'm amazed that others can use frames with a flex of 70 and full poly. YIKES! :shock: This and some other recent experiences with stiffer frames and even poly mains has convinced me to "stay in my own neighborhood" at the corner of Stiffness 60 and Gut Mains.