IMO, I do this for 2 reasons only...I use .011s and by top wrapping the action feels a little lighter with the heavier strings and it also helps in eliminating string breakage. I cant say that sound or sustain is a huge difference, I've heard many sate that they get improved harmonics. Lastly, a few great names that come to mind that *do* top wrap are Joe Bonamassa and Billy Gibbons.