In article , Stefan Patric
wrote:

I would keep the RZ system, and sell off the 645 now while it still has
some value. The RZ should hold its value better, since it was really
designed for professionals, where the 645 was marketed more toward the
serious amateur. Plus, if medium format digital backs ever become
reasonably affordable, I'm sure there'll be one to fit the RZ.

Agreed. I never cared for the 645 format. It appealed to wannabes.