Thank you all for the valuable input. I did not consider a 4X5 with a roll film back, but it's worth the thought. I was aware of the film flatness (or lack thereof) issue and you made me reconsider it.

Also, having owned a Mamiya 7II system in the past - and got excellent results - I think if I want to go back to 2X3 I should re-consider the Mamiya 7II.