As I have spent a lot of time reading these forums, I thought it appropriate to give something back. Thank you all for the information and debate :-)
So, here goes. About two weeks I swapped over my Hasselblad H5D40 for an IQ260, 40-80mm SK lens, ALPA STC and Rodi 32mm HR. The ALPA and Rodi are on their way. This is just a couple of weeks' experience and just my initial impressions.
Why I swapped - Longer exposures (4min Hassy vs 60min PhaseOne); full frame; better screen; better camera workflow; CaptureOne support; more pixels.
What I found - Long exposures requiring a dark frame is a pain in the arse. Over the Hassy, I don't see any noise improvement but perhaps that's the price of a 60mp sensor.
Full frame -Yep, it's a huge and amazing change. The image perspective is amazing.
Better screen - Yep, the Hassy screen and UI are not so good.
Camera Workflow - Interesting. The PhaseOne is much more powerful but adds more time and scope for stuffing up, as a result. The Hassy workflow is much, much simpler. It's a film vs DSLR choice, I think. I like both.
Capture One - For the Hassy you must use Phocus for the best results, CaptureOne for the PhaseOne. Neither camera systems are compatible with each other's RAW processor. I've used Phocus for a year and CaptureOne for two weeks and CaptureOne destroys Phocus. I would do 20% of my processing in Phocus and the balance in Photoshop but with CaptureOne, it is the opposite. RAW files are way more pliable and this is an unexpectedly significant benefit.
More pixels - Makes a difference :-)
Overall - Very happy.
So, hope of interest.
I've attached a shot from the IQ260.