So you think still cameras that can also shoot movies are new? Mais non!
I had a chance to put a Debrie Sept through its paces a few days ago, and I must say it was pretty impressive in its own special analog way. And a few short clips that I saw projected were of excellent photographic quality if you don't worry too much about steadiness and are able to express yourself cinematically in very short takes. And it can also double as a projector and film printer, can your 5D do that?
http://www.camerapedia.org/wiki/Debrie_Sept