To me, it seems pretty straightforward that you can buy (3) $8,500 Pentax 645Z cameras and still have some spare change left over vs. buying (1) IQ250 1-lens system...
That would leave you with (2) extra backup bodies, just in case you need to service one. Heck, you'd still have a backup body if you sent in the first, leaving you with "only 2"...
Heck, buy 2 bodies, so you have a backup, and you won't have to wait that ~24-48hr period for your "loaner" body to arrive on location

Is it just me that the above seems logical? I'm interested in checking this camera out when it finally launches. I prefer to shoot film, but now traveling for work, digital is a much more competent choice due to lack of labs and time to get things processed. I really like the Pentax 645NII system, just wish this 645Z took a traditional screw-in cable release like the 645NII does...
-Dan