The main difference is there is no Fan in the H3d-II. So no noise when solently workin

but also no more moving parts that might break down. I have had both and image quality is stunning. I now only have a H3d-II 39Mp multishot version but i want to sell that for buying some more pixels ;-)). (less than 5000 exposures, as new in other words, 13000 euro).
The lenscoorections in flexcolor and Phocos do a remarkable job, absolutely perfect images without fringing ( not grayed out like in photoshop but calculated out of the image) or distortion.