I had the ZD camera for nearly 3 years & it served me well. The buffer rate was the same as the ZD back ( 11 shots) The new ZDb is 22 shots. Uses the Dalsa 22 mp sensor which likes light & works very well for studio use, I used mine more for landscape which worked very well. Then we got the 1DsMKIII & I could see very little difference plus the Canon has been brilliant so I sold my ZD camera. The concept was good just needs an update at a very good price. If you see a ZDb back used for 2500-3000 range it could be worth it if have AFD glass sitting around. MEF files can be processed in PO, LR. RD, Bibble.
Denis