I think much of "ergonomics" is subjective. Do you like buttons, or dials? On top or behind, etc.
In particular, "holding the camera" is definitely subjective. I've always found Canons, Nikons, (Mamiya/Contax) style of grips to feel tenuous to me. I think my hand is too big or fingers too long and I feel I'm not using my entire hand to hold the camera. The H3DII fits into my palm, which allows my fingers to have more of a grip. Also, I find the rest spot for the thumb and also for the index finger to help greatly in reducing stress from the wrist - especially with larger lenses. I can use my thumb and index finger to help grip, and this I find harder to do on other cameras.
This was always my biggest complaint with the Rollei 6008 - there was no adequate support for thumb/index fingers. I feel like I'm holding a coffee pot. The Hy6/AFi improves this significantly with a fuller grip and better nesting positions for the thumb/index fingers.
Regarding hand holding - I find the H3DII holds up better at low shutter speeds when hand held due to the slight dampening and verticalization of the mirror. I believe this is mostly due to the heat sink in the bottom of the digital magazine, which adds a bit of weight and (at least in my experience) acts to dampen the mirror and produce the effect more of a straight up and down mirror slap. On some H1/H2 cameras, the mirror slap sometimes feels almost like it slightly jerks sideways, rather than just an up and down effect.
As Paul mentioned, the mirror delay (custom function 31) can also help separate the mirror action form the actual shutter release. I would guess this has added up to a stop, stop and a half to my low light shooting. This is available for any H1/H2 camera, not just the H3DII.
Steve Hendrix
www.ppratlanta.com/digital