@Arthur ...
I'll have my K-3 next week hopefully. I'll be able to try a few things in real life.
I'm not actually expecting to use the AA option, i.e. I'll only shoot with it off and handle the rare moire issue in PP
Any D7100 comparison should be done with the same glass and aperture. (eg maybe a Sigma 105/2.8 at f/4 or whatever)
Also: the K-3 sensor is not the same as the D7100 - it is a newer Sony sensor