I got a good offer on a 5D MKiii recently, but despite the raw and overall superior image to 600D I've just stuck with the latter for a few things that are coming up because I know it, and the cost won't improve the product enough.
I could also borrow a BMD M4/3 for these shoots, but still, it's an unknown factor and delivery is PAL SD (yes, SD!), so I think the 600 will be fine.
I that situation 4K and raw are overkill, I just want to make the piece and deliver it as quickly and efficiently as possible, quality is not the priority, and would go un-noticed. Five friends who barely shoot ever own 550Ds that I can borrow as other angles! FIVE! That's market share...
When it's my own work however, music videos and films and so on, I'd like the best I quality can get, but still within reason. I love raw manipulation, so much freedom, but right now the idea of having multiple terrabytes of rushes and a long, long workflow feels like it'd slow me down a lot, plus it's expensive to deal with and presents archiving problems...
Shoot ratios on music promo and narrative are both high. Documentary can be insane, 100:1... there I'd probably use an RX100 (and a million batteries) but raw would be project suicide with current technology.
If ML could code RAW compression (down to 10-bit from 14-bit colour, some lossless compression) into the 5D MKiii it may become more practical, but now it's pretty mental to handle, and I keep reading about lost clips and so on.
I think that's why out of all the BMD owners I know, none have actually embarked on a truly ambitious full project with raw.
***
The last short film I did was for Virgin Media Shorts, I used the 600D with hacked high bitrates and antialiasing filter and I'm happy with it. Sure it's a limited look, but so is certain film stock. I had to work so quickly, I just couldn't have done it with a glitchy camera, too much weight and rigging, or a demonic workflow. I just ran with the look and gave it a grungy psuedo 16mm feel.
If I could've had an Alexa look from a small DSLR box (as BMD promises), complete with compressed ProRes or DNxHD, then it would be the best option, but right now I hear a lot of grumbling from those using those cameras in the heat of battle so I'm keeping clear.
I loved Upstream Colour.... you could tell it was an 8-bit cam and quickly shot in places because the colours were different on every shot, sometimes in the same scene, but it worked with the piece, the confusion and surreal settings, it all added to it.
I think the key is working with what you have. If you have a camera that makes footage look like video, work with that look, if you try and make it look like Red Epic, you end up looking cheap, and so on...
I see a few films shot on Epic where they've tried to emulate film stock and the result is actually too sharp to be believable, so it works both ways.