I'm really impressed by LinuxMCE but one component I see as dated, and it is not fault of LinuxMCE but of upstream project. That component is MythTV. There are a lot of users who don't need recording just great media front end, and that is what XBMC is. I have tested all media center for playback of media and for me XBMC has no competition.
XBMC is also modular and backend playback can be xine, mplayer maybe even VLC, not 100% sure about last one.
Hope I get my 100k from LinuxMCE business as soon as possible so to sponsor this feature
EDIT: some of you have missed smiley face in the last line, and no, I currently don't make any money on LinuxMCE but would love to start a home automation business and then also help this project with donations in code and money.