How does Babolat Ballistic Polymono compare with other poly strings? It is the first poly I have ever played with. It doesn't seem very stiff to me, but then again, I previously used Lightning XX strung at 70 lbs, so anything will feel soft after that. It has good durability -- almost too good -- but I don't know about other poly strings. Can someone compare Polymono to other poly strings, particularly cheaper ones?