I don't know that Pentax ergonomics are uniformly superior (K-S1?), but I do know that the two dSLR models (K10D and K-3) I have purchased suit my hands very nicely and that the "feel" in hand was a consideration at time of purchase. Both balance nicely with lenses in my kit and I am a very happy camper.
That being said, aside from general principles for usability, what works varies from person to person and often goes against conventional wisdom. Examples from my personal experience:
- Love the deep grip on my K-3 and also the K-30 (never owned). K-50 is not so good as the K-30.
- Pentax Spotmatic (and derivative bodies): Despite reputation, these only work well for me with a half-case attached.
- The compact M and A series film SLRs are generally too small for my hands, though the Super Program with half-case and grip is quite nice.
- I like my Ricoh XR7; despite its compact size and my long fingers, most controls fall easily to my hands.
- Of all the cameras on the shelf, the grand prize for handling is shared by two of my rangefinder film cameras.
- Canon P with Zhou case fitted
- FED-2 with hand strap
The Zhou case has sculpted bumps for thumb and fingers...deluxe. With a wrist strap and the original vulcanite, the FED just simply works. Go figure - My recently purchased Bessa R3M should have high marks (light, nice grip, great controls), but I have yet to find a point of resonance with the camera
- The prize for worst ergonomics of any camera I have every held goes to the Exacta Varex...designed to slip out of your hands...the hard you grip the less secure the hold
Steve