I've had my hands on the Canon C100. It is a really cool little camera. The build quality really impressed me. The camera feels solid and professional. Economically, everything feels great and the button placement is very intuitive. The major downside, I'm sure you've read as it's all over the internet is that it lacks a usable viewfinder. But so do DSLR's. The LCD screen, on the other hand, looks really good and I've had no issues focusing my shots.
I'm still experimenting with the internal codec versus recording externally with a Ninja. For most of my work, I would prefer to record externally to a higher codec. There are times when I would prefer to shoot a baked-in look in camera as long as the AVCHD codec holds up. No one really complains about the Sony FS cameras, so I have high hopes.
There is an issue with recording AVCHD. Internally, the camera will shoot and record 23.98p, and you can edit true progressive footage without a problem. What if you want to shoot 29.97p? There is no option to shoot "native 30p". The camera only does what Canon calls 30PsF. From my research, this means that the camera is shooting 30p natively, but wraps it in a 1080 60i container. My Atomos Ninja 2 can decode that in real time and record the proper progressive frame rate, so for most of my work this isn't an issue because I wouldn't hand clients AVCHD files except as a backup recording to the Ninja.
Sometimes shooting AVCHD might be the best option. For instance, if I'm working run and gun say on a documentary shoot, carrying around the extra bulk of an external recorder is not practical. Internal recording might make the most sense. If I shoot 30p, my footage is stored on the SD cards as 1080i and not 1080p.
When I import the media into Final Cut X, the software, does not recognize the progressive frame rate. It wants to play back as interlaced footage because that iw what the wrapper is telling it to do. Don't panic, there is a simple fix. Here is how.
Select all of the 30PsF clips in the Event Browser. I have already "optimized" or transcoded to ProRes, but you don't need to. After the clips you need to adjust are selected, show the inspector window. You will see an option for field dominance. If you change that to progressive, all of the clips are now displayed correctly as 30p clips. Just make sure that your storyline is 30p and you are good to go.
I hope this helps ease some confusion. I know I was in a panic when I played back my footage and it was interlaced!.