[da-anda]

I'm also for consistency, but up/down is also not consistent yet. If video has chapters it jumps chapters, if not it performs big jumps. In music playback left/right is seeking like in video, but up/down changes rating instead of big jumps (which could be useful for audio books f.e.). So my personal aim would be:

up/down context sensitive:
- switch chapters in video playback
- rating up/down in music
- channel up/down in PVR (at least on remote with limited keys)

left/right consistent:
media portal style skipping/seeking all over the place

Also the up/down mapping should depend on the remote. On remotes with only a few buttons it should perform channel switches - on remotes with dedicated channel buttons it could be used for something else.