I bought a fuji g617 rangefinder to give the format a try. I still have it here but it's officially someone elses now. I found it pretty limiting to be fair. The 105mm lens was too wide for my taste. With a rollfilm back, even though it's slower to set up you're going to get an exact representation of what you're getting on film, You can get a good idea with the Fuji but it takes a bit of time to get used to, the rangefinder window isn't all that accurate. Then there's the ability to use different lenses, if you already have some for your 4x5 then even better, and you can use camera movements. haven't used a 6x17 rollfilm on my 4x5 but I think if I went for 6x17 again it'd be more comfortable on a 5x7. Thinking about it though, I reckon I might go all out one day and get an 8x20"