
Wowza. Here is where I think the logic fails a bit - if you are putting significantly fewer pixels in a area, this level of crop is simply going to have a lot less data to work with if it came off of a 5D3 - sometimes you need pixels for prints, or certain DPI numbers for publishers, and an APS-C keeps that density higher for longer when cropping in.
Without cropping my FF kicked my crop when I used to play around with my MP-E 65 but I always assumed I had an edge to pushed crops with my crop just because of the pixel density. I have no data to back that.