I've read of reports of grain in dark areas of well lit images and mild washout. All these sound like adaptive dynamic range and dual slope that sensors use to get more range. The washout or noise, is the price paid to get the extra range, but the HC1 images look much better than any of the extreme sample images I've seen using this.

Heres a sample:

http://www.smalcamera.com/v1000camera.html

The CMOS chip on the HC1 is very may be a great breakthrough for Sony, but for my money the more hours I get on the cam, the more it's starting to bug me.
On a perfect summers day it's possible with a polarizing filter to get bad grain in the sky and at the same time knock out the contrast in the rest of the picture. Other weird effects over the last few days include lovely HDV footage in bright light of sky and background, but with shadows on faces and trees throbbing with grain that looks like poor nightime standard dv.
Just like the curse of auto gain on sound, Sony has now introduced the same problem for the picture.

Yes that sounds a bit like it. If lighting is too extreme, or it is not done right, at least one of the extremes (or the middle) would suffer.