I have used the much loved (Beatie?) after market sceen and a split RZ screen, and both are tough to do critical focus. This with 2-4 250w modeling lights(still need to squint with my 20/20 vision). I use the prizm with a magnify loop on it, that flips up. This is the best method I found. As far as the lens I like.... the wide 37, its fun, 180, 65 and the 140 for serious stuff. Focusing is a bit differnt on the RZ glass as it has the distance ring, and this on the 140 makes a difference. Its been a few months since I have used it, as I got tired of trying to figure out the motor drive to lens setting (M,R..etc) and what shutter release setting it needs to be on (white dot, orange, ?), etc. The issues I had with the RZ, I am sure are things I didn't allow to really sink in for me to be fully grasp, as I didn't need them on a day to day basis to be natural with the system. That can be with any system. Having said that....
I think the RZ can do everything the Hy6 can in regards to the points Foto-z makes. As much as I love a well made durable product like the Hy6 looks to be(the RZ's plastic on the WLF corner where you lock and unlock it from the body has chipped off, yet still functions and locks).... I can't see where it makes a $10k+ leap over the RZ as a MF system. I finally put it aside when the limitation of the Tiltshift bellows and the fact that you really can't measure your extensions without jotting things down, for me had too many drawbacks for my shooting at the time. Are my Rod glasses better, yes, but depending on the subject, is it detectable. I will still use my RZ for the jobs that fit best for it.
What are the main benifits of the Pro IID vs the ProII....As far as using a PhaseOne back with it (not a Mamiya back)? I would think you still need a RZ to V adapter (for v backs)?