Hi,
It works, I am using Github successfully for several years, never tried perforce, and we know that Unity own collaborate tool is buggy and doesn't play nice with PlayMaker unfortunatly, so we do not recommand using Unity own collbarote system.
the key is avoid concurrent editing on fsm components, because PlayMaker internal data ( states, variables, links) is serialized in one chunck of binvary data, it would not be possible to make a diff of changes between two concurrent commits easily ( if at all).
given that, it's ok, the same apply with scenes, images, animator, animations, and many other aspect of your Unity projects.
The key is to commit often, litteraly almost at every step of the way, I can commit 10 times per day, each commit being very precise and contextual. Don't commit everything in one go, cut it down ( added asset, modified scene, etc etc)
this way you minize work loss should unsolveable concurrent editing occurs. Which it should not if your team is organized and you are communicating throughout the process. Be always reacheable via a live chat system of your choice, say what your are doing, what you are going to do, use a planner and a task manager, and stick to it, then it will be smooth ( as smooth as it can possibly can... )
Bye,
Jean