David,
Personally, I've never shot anything MF larger than 6x9, but I've seen photos of 6x17 aspect and would entertain the thought of something wider. I looked at the 6x24 offering. Looks like fun, but I'd prefer an adapter to use with a field camera.
Does a 6x17 work properly on a 4x5? 17cm is longer than 5 inches. I can understand the 5x7 function, but I have an 8x10, so I'm feeding my own selfish thoughts right now!
Chris