peter, i just uploaded superflat to my 7D yesterday. do you use superflat during the day in sunny conditions? do you use it to shoot interviews? i've read it's hard to color correct faces or give faces color.
I personally use "superflat", when I have (extra) time for cc in post. If it has to be fast, I use "neutral" (with sharpness and contrast turned down completely and saturation turned down two ticks) which is a bit easier to grade but won't give you the possibilities "superflat" does.
I use these profiles for almost any kind of situations but must admit, I haven't shot any interviews with my DSLR, but haven't had problems with skin-tones with either of them.
I work a lot with Premiere (levels, primary and secondary colour correction) and also use After Effects a lot (levels, curves, hue/saturation and/or Magic Bullets Colorista).
You might want to take a look at "Marvels Cinegamma" (http://marvelsfilm.wordpress.com/2009/10/19/canon-7d-picture-style-with-cine-gamma-s-curve-free-download/). It's a great profile for working cinematically.
There are mixed opinions on using custom 'flat' picture profiles on DSLRs. I have a couple of them stored on my T2i but have to admit I don't like the look of them. They make skin tones look weird especially IMO. I prefer to use neutral with contrast, saturation and sharpness dialed down.
The canon DSLRs as far as I know don't have a great amount of dynamic range compared to traditional video cameras. Blacks look especially crushed particularly in underexposes areas. Flat picture profiles are supposed to increase dynamic range but to me, all they do is reduce contrast to the extent of turning blacks grey and introducing extra noise in the darker areas of the image. You get a little bit of extra detail in the dark areas but in a way where you're compromising overall image quality.
Everyone has different preferences and workflows so I'd say do your own tests and come to your own conclusion.
My advice: shoot neutral, use a fast lens when possible and don't underexpose.
Glad I helped!
Did a short test today with the new style and it looks way better than "superflat" imho. Haven't been able to do some grading tests but hopefully will be toworrow. Seems to be a great style!