well. if you are talking about additional buttons, not all mouses are going to be supported.

http://www.reddit.com/r/ffxiv/commen...ill_work_with/

one comment that stands out...

"Perhaps this is stupid and completely wrong, but I'm guessing that the mice that will work are ones that have the drivers installed on them (those that can save profiles internally) versus those that don't have on-board memory?"

so you may want to keep that in mind when looking for a new mouse.