Thank you. Reading Sigma’s website you would think it was the second coming. I have a Nikon, happy with it.
Yes, I have an old Pentax DSLR with only 6mp and it seems to be completely adequate. Also a couple of old Sonys with 12mp pixels. I can’t really tell the difference.
One of the biggest improvements in addition to more pixels is they now have far less noise and will operate at ISOs which my old cameras would only show darkness.
One thing to keep in mind is to double the resolution you have to quadruple the number of pixels.