I imagine it'll depend on what you want to use the camera for. In the middle of the jungle with limited power available, I suspect the C300 is the one to go for. Also, if you want to shoot at very low light levels.
There's a discussion about both cameras here:
The C300 does come out pretty positivity during the conversation following the experience of using the pre-production cameras.
Edited by Brian Drysdale, 14 November 2011 - 03:18 AM.