Just one thing to consider with the C300 is that the hand grip is towards the rear of what is a very short camera. Put a 24-70mm L series lens on it (as many will) and you cannot hold it single handed for more than a minute as all the weight is in the lens, it's really front heavy. Most handy cams have longer bodies and the grip is usually closer to the centre of gravity.

True: found this out this afternoon. The hand grip seems to be on the right place when you shoot without lenses ;-)
I also think it would be nice when the hand grip can be adjusted, just like an EX1R can: push button and rotate.

Put a 24-70mm L series lens on it (as many will) and you cannot hold it single handed for more than a minute as all the weight is in the lens, it's really front heavy.

Put the 24-70 on any camera it fits on, and that camera will instantly become front heavy. :-)
(and I'm not sure why you would ever single-hand a camera of this size, configuration and weight)

FWIW, I spent my birthday week in NYC toting around the C300 with the 17-55 2.8L IS. First, it's an incredibly useful configuration, I had no problems with the weight or size, (and I'm a wimp)...Second, I was able to get tripod quality tilts and lock-downs hand-held, and thirdly...when shopping for a "travel bag" for the c300...I've never seen such curious salesman at b&h...("can I hold it?")