As others have said, the Sansa products are pretty stable. I have a Clip+ that has been rockbox'ed along with my iPod 4G Color and 5G. All 3 are running like champs, but there are some items that people need to be aware of. USB transfer on the Clip+ isn't there within Rockbox as mentioned above so booting in to the OF is necessary for this. Even the more "mature" versions on the iPods have some problems (ex. charging via USB...there is a patch, but it isn't part of the current builds yet).
I have a modified script, originally written for the Clip, I use in iTunes to transfer any of my playlists along with the music in their appropriate directory hierarchy. The music is copied over as /Music/Artist/Album/Song and the playlist is placed in /Playlists. This works for both the Clip+ and iPods since it is just looking for an install of rockbox on a mounted device (Clip+ SD card is another story, but can be worked around to work). This was the last thing I needed to transition 100% to rockbox as I have used iTunes on a Mac since it was purchased as SoundJam by Apple many years ago, and I have a lot of playlists built up. This is an AppleScript, so it is Mac only, but I'm not a fan of iTunes on Windows anyway, so even if I ran Windows, I'd use something else....rambling now, sorry.
As for video, rockbox does support video, although I will admit that I have never tried it, but the support is there for at least several of the iPods.