I did 1 movie with the d-20. It is a bit of a pig with the flash mags, but I thought if flew very well tethered. I ran a very light weight jumper BNC from the camera to my arm where I had a real BNC running back to my vest. The DIT didn't see any problem with it. He was from the EU where they run 100 meter HDSDI runs all the time. It is front heavy with an S4 and no flash mag.
It was a huge battery hog, mostly because we were afraid to turn it off. If we shut down, about 30% of the time we would get a bad reboot, would have to shut down again, reboot, the DIT would have to come over make sure we had a good boot, then we could shoot. So as a result we just let it purr right along sucking up my batts.
It doesn't like to get extremely hot. We had it refuse to respond to the helm a few times on interiors where the temp hit 105 or so. Refused to stop the mirror shutter, wouldn't turn off.
Everyone in the camera dept wanted to love this camera. In the end we all really wished we had had a varicam.