I'm grappling with these topics in that I'm getting back to film after a long absence. It really was the realization that I should either sell my equipment, or use it.
So, I've been out shooting my Mamiya 7s and Contax G2 systems with various films. What is clear is that I can carry my Contax all day..every day. My 1DMKIII is a great camera, but I don't/won't carry it. So, I'm thinking 35mm for mostly traditional B&W, but I would not consider shooting 35mm without knowing that I was going to have a quality film scanner. I've not yet sorted the Mamiya side of things, but i think this will be a question of do i carry the Canon, or the Mamiya? I see them filling the same nitch, with the Mamiya doing a better job of more static images and the Canon being a better player when shooting moving objects, like my kids.. So, I started this film thing expecting to sell the worthless 35mm and shoot the medium format for quality results, but I think that i'll be shooting more 35mm B&W than either digital, or the MF. It really surprises me to say that , because I started with the sense that anything that I could do in 35mm could better be done in digital. I no longer believe this.