I've used this wide angle lens for video on my 7D for a good while and love it.
I got an adapter for the GH2 this week and so far, still love it.

I'm going to give it a full blown workout on Wednesday, then I can see any pitfalls.

I also have a Canon to 4/3 with a built in aperture. It will be interesting to see how some Canon Lenses do.