I won't try to convince anyone else to get one, but I have to say I really love the Pentax 6x7. I have used it on a tripod when appropriate, but since it handles just like a "grown up" 35 SLR, it's great for spontaneous hand-held use too, as exemplified by the attached shot (couldn't resist sharing one!).
I've three of them now, the first a used non-MLU model in 1976, the second a used late 6x7 in 2003, and I just got a brand-new 67II this Spring. Err, BTW I really dislike waist-level viewing though quite possible with these cams! The shot below was hand-held in 1981, 55mm lens, Ektachrome 200, at Black Rock, Kaanapali, Maui, with Lanai in the distance.