I have been using the Kinemax and Terra for years now. Great imge quality for an unbeatable price. The Terrra shoots straight to Prores 422HQ. Great dynamic range, natural color profile, ability to shoot log and anamorphic. Shoots 4k up to 100fps. Low noise. Really cant beat the packages for the price.
You can also shoot with the lens detached from the camera body. It lets lots of light in from the sides of the mount. The hardest thing is focus, as it will change with any micro movement of the lens forward or back.
I've had some success shooting the old medium format lenses detached as the glass has some wiggle room on either side vs a s35 sensor.
I'd recommend the fs7 over the fs5. The fs5 is really noisy by comparison. The fs7 will give you much more latitude over the c100 and great slow motion capabilities.
In side by side tests, magic lantern produces a much better image out of the 5d than a BM pocket. Way more color and sharpness. GH4 is probably your best bet though even though it isn't raw. Shootout:
Or if you could try to step up into an entry cinema camera:http://www.kinefinity.com/shop/terra-basic/?lang=en
These guys are extremely cheap for what you get with tons of customization and the best image quality under an Arri.
I bought a kinemax 6k last year and so far, have loved it. To my eye, much better, more natural image than my scarlet dragon. It did have an issue and I had to send it back to china for service. They paid for delivery but it got stuck in customs for a month. Luckily they are pretty damn affordable, so I currently have the Terra 5k on preorder as a 2nd cam/ backup in case one goes down.