Chek-Mate did some testing to answer this question some years ago. They had a "pro" shooter test a bow that was tillered for split, one that was tillered for 3-under, and one tillered upside-down (basicly, for 3-over). After tuning, he was just as accurate with one as the other. The only difference they observed was a bow can be a little noisier if tillered for 3-under and shot split (or vice-versa). it won't damage the bow, but you will probably have to make adjustments to the nock set, silencer placement, etc. if you switch from one to the other.

Chad