I am also enthusiastic about using an Xbox 360 S (largely because it's wireless is much faster and I'm not able to reasonably do wired), but find that ffwd/rwnd (fast forward/rewind) don't seem to work regardless of the options I've tried, whereas they seem to work well with the ps3.
My scenario is:
PS3 Media Server 1.71.0 hosted on Win 7x64 i7-920 w/ 6GB ram, running on system disk that's an SSD.
Streaming DVD backups (just a pair of video_ts and audio_ts folders each) over wireless n via WNDR3500L netgear router running Tomato.
.. To an Xbox 360 S.
I'm happy to provide config or log file copies.
It sounds like maybe transcoding never works with fast forward/rewind (which I guess is actually time-skip?), and so maybe the issue is that the ps3 isn't transcoding those videos and so ffwd/rwnd work, whereas the Xbox 360 is always transcoding (b/c of the settings shown in the last post) and so ffwd/rwnd never works? Is that right? And if so then maybe I could just amend the Xbox.conf file to show that Xbox supports mpg2, and then it would only use remux if I didn't go into the Transcode folder and ffwd/rwnd would work?
It also seems like, on the Xbox 360, videos may exit/ stop streaming on their own after about 15-20 minutes .. but I haven't played with this too much as I haven't watched that much yet because of the ffwd issue.