I have been use my Canon 7d for casual videotaping for long time, and I recently added a 60d to my work flow. So sometimes I can have multi-cam set up.
I have heard so many praise about Panasonic GH2 for years. I heard it is the best video camera (after hack) in term of resolution for under $3000 for now.
So I finally bought a second hand GH2 at ebay. I can say the quality of the video is way better than my canon dslr.
gh2 is just a lot better than canon dslr. especially at wide angle, it is very obvious. When subject get close, canon dslr is quite sharp too. Mind you that I have turn the sharpness all the way down in both camera setting.
Both lens used is quite sharp. Pentax M28 f2.8 at f4 for gh2. Canon 17-55 f2.8 at f4 for 7d.
The moire is crazy in 7d and 60d. I believe it is more intrusive on 6d. It is cured on 5d mark III. but the rest of gang all suffer from it. However on gh2 it handles it so good. Only slight hint of moire. I researched that gh2 handles moire better than gh3.
3. recording time/overheat
Gh2 has no limit on recording time per one clip, and it has no overheat issue. Whereas most canon dslr can only record around 11-13 mins per clip. And canon dslr can easily got overheat when temperature is high. Again 5d mark III improves a lot here. It can record 30 mins and seems no overheat issue that I researched online.
Overall if you mainly doing video. I would suggest invest in GH series and their lens. Since I mainly doing photo, I still find Canon is a better choice. but who knows what Canon will come up in their next model. They may improve their video spec a lot. Who knows.