I'm mostly interested in 617 because I can do proper panoramic, as I hate stitching and just can't get on with it. Film is the only viable option for that format at the moment for a hobbyist. The Seitz 6x17 produces amazing images, but its a scanning back so you can't use it on anything moving, and its around £70k..
Red are also bringing out that 617 monolith thing, but its like £100k or something lol. It'll still be along time before digital gets affordable access to MF/LF quality.
I'm also amazed at the quality of LF lenses, if I go for the Technorama, the Schneider super angulon XL lenses are on a totally different planet from anything on 35mm.. Goodbye to mushy corners, distortion etc..