May I also agree with all the comments as well.
I have 2 x GH3s a GH2 5DMKII & III etc, I shoot freelance news media and though the 5D is the low light king, the GH3 has a brilliant crisp clear colourful image, it's small and takes so many lenses plus the wifi is great.
But having said all those nice things I just bought a Canon C100 video camera and wow!
The picture is just soooooo clear yes even clearer nicer than GH3 and the audio is proper professional high quality sound it's noise free and full bodied.
For your skateboarding the GH3 is the way to go, you will love it.
I just wanted to put it out there that the C100 is a serious movie making camera and as much as I didn't think it possible, as good as DSLR video is, and the GH3 is at the top, the C100 though more expensive is what the 5DIII pretends to be.
if anyone wants to graduate up from DSLR video have a serious look at the C100.
low light is better than 5DIII depth of field almost on par with full frame and lots more stuff.
Even the battery life & choices are a gift.