Most engines I've ever dealt with are able to use both Biped and Bones. We've even used both in one rig before (Biped with extra bones hanging off). In the end all that the exporter is doing is pumping out rotation and position values to the bones in the engine so it theoretically should just be some extra work for the…
Our engine supports both custom rigs and biped rig exporting, but personally, I really don't like the biped. Every time I try to animate with it I just end up really annoyed. I never have been able to get used to it's quirkiness. For several years I just made a new custom rig for each character, but that was a lot of work.…