Interesting discussion. There's medium format and there's medium format. In his book Field Photography A. A. Blaker makes the point that moving up in format isn't worth the trouble unless, if I recall correctly, both dimensions of the frame are at least doubled. If you buy that, well, twice 24 x 36 is 48 x 72, which is lower and no longer than 6x7. And if you buy that 645 and 6x6 are too small. 6x7 is the first step up from 24 x 36.
Short lenses for 6x7 and 6x9 can be very costly. I shoot 2x3 (6x9 in metric) with Graphics and a 2x3 Cambo. My shortest lenses are a 35/4.5 Apo-Grandagon, a 47/5.6 Super Angulon and a 58 and and a couple of 60s of which I prefer the 60/14 Perigraphe. 24 x 36 equivalents are 15 mm, 20 mm, and 25 mm. Go price 'em. A 65 on 2x3's 35 mm equivalent is 28 mm, an 80's is 34 mm.
If I were constrained to 6x7 and wanted to give up tinkering I suppose I'd go Mamiya 7 or, maybe, Pentax 67. Back when I passed on the Pentax because of its low flash sync speed.
OP, since you're open to press cameras you might want to read this: http://www.galerie-photo.com/telecha...2011-03-29.pdf As you'll read, I use Graphics. My first 2x3 camera was a Busch Pressman. Attractive, but for a variety of reasons including size of the front standard and availability of lens boards I much prefer Graphics. A 2x3 Speed Graphic can't use short lenses as you're interested in, its minimum extension is around 62 mm. If you go Graphic (think hard, I like 'em but they're not for everyone) you'll want a Century Graphic or a 2x3 Crown Graphic with a Graflok back. Learn more about Graphics on www.graflex.org
Good luck, have fun,