Not sure how many others have used it, but I have used the metademolab (and recommended about it) a couple of times for game jams, and my latest was actually with characters from pixelvibe (only one ended up in the game though). It can work like a charm but it takes some fiddeling around and sometimes small modifications of the characters that comes from pixelvibe (they often have robes or long clothing that doesn't really work well with metademolab).