I can't speak for direct comparison but I find the lens correction in C1 to be excellent. In particular the sharpness falloff correction, chromatic aberration removal, and purple fringing removal I find to be consistently better than any other processor with the least complicated controls.
Is the latest version of high megapixel backs require more lens corrections?
I've used my Contax and p21+, p30+ for a long time and never used lens corrections. Admittedly, I don't shoot interiors or architecture so lining up walls is not that high on my list, but I do shoot into bright backlight, sidelight, fairly long exposures, mixed with flash and practical lighting and rarely, very, very rarely have ever seen any CA, or lens detraction.
In fact we just finished a project where we want more grit to the image so on the p30+ we shot at iso 400, which put me at F 16 for the majority of the shoot. I never saw any softness or detraction from those old zeiss lenses, in fact they are freaky sharp. If anything those old zeiss lenses are sometimes too sharp.
One thing I have noticed with my cameras is how much better the look of processing is in the last two years, with C-1 and the latest versions of Lightroom. Previously I thought the Phase backs were way too color sensitive and now it seems that skin tones are much more manageable and ambient color seems to pollute the image less.
Anyway, my point is, do the very high 50mp and 80mp cameras more sensitive in Focus, CA and detraction?