Alberto... Oh yes!
My humble opinion is because of the new firmware update and new hacks and understanding of certain areas the GH2 can in terms of picture quality compete rather nicely with cams like the C300. Unless you need 4,2,2 for greenscreen.
But then put £650 for the GH2 against the £12000 for the C300 and really it's a no brainer and who knows you could buy the C300 and a hack is found for the GH2 to deliver 4,2,2.
Of course though another hidden expense is you still need a good matte box, ND filters and a monitor. The good thing is when you have those things,any new comparable cameras with those things IE lenses, come with you!
I really think DSLR style cameras could be the way forward for film makers. However NAB could pull out a comeback.
Exciting times but maybe the wrong times to invest heavily!