I say that a 35mm with an interchangabel back is a great idea. For those of us who can not afford the luxery of having a body for color and a body for b+w might find this inticing. With interchangable backs, a digital back could also be made available. Think about it. I wish more up to date digital system was available for my F3, as well as an interchangable back option. That would be amaizing! I could have the best of all the worlds. Color, B+W, and digital. There have been tons of situations where I found myself indoors unable to use a flash and thinking to myself "I wish this wasn't fp4". Also a hybrid shutter is a great idea. Carrying extra batteries is great, but electionics are unreliable in some conditions. Also, some people are just forgetfull, batteries are no good if you left them at home.