I'm a 4.0 and my racquet is in my sig. I played against a 5.0 tonight and got my ass handed to me. All my backhands were late and I was spraying most my errors to the court on the left. Made a lot of errors when he served out wide to my backhand again. After the match my arm was so sore and it got me thinking, do I really have any business using a 11.9 ounce racquet? Sure when i play with my co-4.0-4.5ers the heavier racquet gives me a lot of power and spin. But is it all just a fallacy?