Actually I evaluated pretty good results with PS3 Media Server + ffmpeg 1.2 + Oracle Java 8 Preview on Raspberry Pi. I used ffmpeg in remuxing mode (video + audio) and on first glance 720p files play very nice, no visible stuttering. So it may be considered as tsmuxer replacement. Audio streaming works nice too, no problems with FLACs on PS3.
By the way I have 512 Mb R-Pi model and I think this amount of RAM is bare minimum requirement with current PS3MS buffer implementation. Bad luck 256 Mb model owners.