I guess user experiences vary greatly.
I purchased a well used H1 (100k shots on the body and 30k on the lens shutter, does not looked abused at all so I guess it was used mostly in a studio environment) with finder and 80mm lens months ago and have had zero problems using it with my IQ160 from day one. It is not my main camera to use with the PhaseOne back since I mostly use the Arca RM3di but it has worked flawlessly so far whenever ive needed it. I basically got the H1, charged the battery and just used it. Did not do any maintenance or checked the firmware or anything. It was a rental camera. AF works very well.