If you're shooting docs, I can't imagine the amount of CF cards and hard-drive space you'd need to shoot raw with ML. Yes, you get a ton more color info with ML over XAVC, but the a7s picture looks fantastic, I feel like the color looks very rich. You can adjust your internal settings on the Sony to get closer (not identical) to Canon's color. Color is super important, but does it outweigh everything else that comes with it? Longer workflow times & extra equipment costs?
Keep your 7D for stills, my advice is to go with the Sony. (I own the a7s, Canon 6D & 60D, I love them all for different reasons)
Something I noticed when I saw this camera being featured on Scott Kelby's page today, 1080 60p looks to be IPB only, not All-i.
My two favorite live action films that use color brilliantly: "Hero" with Jet Li, and "The Fall" with Lee Pace.