Thanks all for the comments.
@Jeff - the only one available from Badger Graphic at the time was the PTB617 rather than the TC617, and after looking at the spec, I thought the PTB is better: it's lighter and folds up, and only lose some movements that are probably not important. I like pano format a lot so I know I don't want a 4x5 or 5x7 with a 617 back - that's wasting a lot of the camera features that I don't use.
@Tim, yes it folds up to the size of a hardcover book. Of course you still have the rollfilm holder and the lens....