Well... tried it for 3 weeks and got bored with listening to peoples problems all day.
Finally managed to hold a C300 a few days ago as well as an F3.
I found the C300 very impressive and feels really nice to hold. It had the Canon 17-55mm EFS lens on it.
As I already have a VOCAS matte box set, I'm getting a new vocas baseplate designed for the C300 and the Canon 70-200mm IS.
Plus, as I'll be using the XF300 alonside the C300 and using the double record feature on both cameras, I had to get more 32GB CF cards. B & H were doing them for $75 each. A lot cheaper than here in the UK.