Well, when I changed to 11's there definitely was a difference in playability! What I ended up doing was messing around with the intonation and string height. Going from 9's to 11's I would think that a truss rod adjustment may be in order since there is going to be a lot more tension on the neck. (I would leave that part up to a good tech). I love playing with 11's. I tried 9's but they are just too light for me. I end up squeezing them out of tune.