I've been using Mezzmo with 4 Sony S370s for about 18 months.

I use the Sony BDP (PAL) profile for all 4 players. I find that gives me the best compatibility and the only files that need transcoding are MP4s/x264s. Using this device profile also allows FFWD/REW on all video files.

Of course, as Paul has mentioned above, if you're having problems with stuttering make sure your PC isn't struggling to transcode the MP4 files.