I've heard before that putting heavier gauge strings on a guitar (especially an acoustic) really isn't good for it, and eventually can cause damage or excessive wear to the neck/bridge. Is this true?
Yes I've heard the same I believe it's more stress on the neck, bowing and all that jazz. I use lights myself. You probably don't need heavy strings go mediums that's what most guys I know use & it sounds great!
Well, if you get your truss rod adjusted and stuff when you put the heavier gauged strings on, it won't hurt it.
I have had medium guage strings make both my accoustics unhappy. They like lights, and really there is no reason for me to have mediums. I go for 12 to 52, but get 11s if I can.