You see a lot of ridiculous claims on forums all the time, but the claim that this or that back has better colors is one of the funnier ones. I downloaded the aptus file above out of curiosity and I laughed out loud when I opened it. Take it from a pro that has been using a P25 for 8 years now, and almost every other significant DB and DSLR released along the way, you can pretty much get whatever colors you want from whatever you are using as long as you know what you are doing. Your colors will depend 99.99% on the light at the moment of capture and what you choose to do with the file in post.
"Better" color is kind of a tricky descriptive. It depends. In the case of "better", for a landscape shooter, this may often mean more pleasing or accurate greens out of the box, and also can be highly subjective. And a gain in greens could mean a loss in reds, so tree bark, limbs, stems, terrain, etc, might be considered worse. Or vice versa. Can a digital back produce "better" color for skin than another?
I think the bigger lesson that you're introducing is; break it down - better how? And for what?
When it comes to getting whatever colors you want out of any DB, other than for reproduction, generally speaking, I'm on the same page, but not completely. "Better" color for some, could mean better color out of the box, which negates having to do as much post for color. That resonates with quite a few people. And there are differences out of the box. Different sensor manufacturers, different IR Filters, different color conversion algorithms all affect out of the box color. In most cases, these colors can be modified (either manually or via profile creation/edit), to be very equivalent, though depending on the out of the box starting point and what you're shooting -
and how objectively accurate it needs to be - this may be a more laborious process with some models than others.
Steve Hendrix
Capture Integration