Mark - I understand completely. I have a 4X5 Arca Swiss and when i spring for a MFDB, I will most likely go the 6X9 conversion route. Martin at Arca Swiss recommends micro orbix for use with digital backs. It makes focusing less sloppy and more precise.
I also am heavily invested in a Mamiya 645 system, so I can use that for other work.
The lens cast issues with view camera movements worries me about the Phase backs. I also worry about Leaf switching over to Kodak chips down the road, and I worry about all these backs not holding up to the elements outside.
I have never had a view camera fail on me or stop working because it was too humid, too cold, or too hot. I did have a cinder land on my camera once from a forest fire and burn a hole through the bellows. Fortunately, I had another bellows, so no worries.
I have had to send the Arca in for a tuneup. Try Precision Camera in Chicago if you need this done.