I honestly haven’t had that much experience with cross-platform exchanges of PPro files, but I am guessing fonts may be an issue. Also, if either one of you decides to transcode the footage before working on it (e.g. your mac buddy may not have a fast nVidia card to take advantage of PPro’s Mercury Playback engine), you have to decide upon a common format. Although PPro can decode ProRes, you can’t encode it on Windows (AFAIK). Another deal-breaker might be the plugins you may have used.
Trial and error, I guess…
Richard van den Boogaard
Freelance cameraman • Glidecam Operator • Editor • YouTube expert