I have a friend who strings with me, a solid 4.5 player. He was breaking synthetics very quickly so I strung up some poly for him (hybrid). He broke that fast too, said he liked the poly feel but that's about it, wasn't overly impressed. Last year I strung up some Luxilon ALU for him and he was extremely impressed and immediately told me to order more. And it made a big difference in his game, I never beat him since
So everyone has a different experience out there. I just would never say I couldn't play better with another string because hey you just never know unless you try it. My 2 cents.