Change tables liberally, but not because you lost x% of a buyin. There's innumerable reasons to change tables but I dont think that is really a good reason in and of itself.

Change because your raises aren't getting respect? Meh. Just tighten up and watch them throw money at you.

I tend to change tables when I can't steal someones blind or someone on my left begins to cold call me a lot. When I get to the point where I find myself calling down too light because I think he might be "playing back at me" I generally just leave and find an easier game.