…My question would be would it make sense to try or test any of the older backs on the rb67….
Given the prices for digital backs, the only justification for them would be a significant volume of professional output. In other words, they are just too expensive for casual use.
I have given digital backs some consideration and, since I can scan very fine grained film with a scanner, there does not seem to be an economic justification for low volume work.
I have an Epson V750 with an aftermarket carrier from betterscanning.com (under $1,000 combined) that gives me results almost as good ad my Coolscan 9000 that I got five years back for just under $2,000 (no longer made). With T-Max and Portra films I can make huge prints if I want to.
Among other benefits, I feel no compulsion to upgrade my equipment to keep up with advances in digital technology, which is the ugly side of the digital world.