Jon, I think your supposition about #4 Panorams being shelf queens is probably quite correct. Specialty house film to fit them is very costly, and using them as single shot cameras with sheet film or making "roll your own" out of aerial film are both a big pain in the butt. So, I suspect folks, like me, who want to take pictures will settle for the #1 Panoram (even though it has only a 112 degree swing rather than the 142 degrees of the #4)
On the other hand, in order to take advantage of the greater swing of the #4, some folks have made 2 1/4 masks plus some insert plugs to center the 120 film roll to line up with the mask in order to easily use the #4 to take 2 1/4 x 10 1/2 negatives for a 4 to 1 + panoramic ratio.
By the way folks, those German 1.6 x 8 mm oval head brass screws are really nice, and that 0.1mm extra thread diameter compared to our old #0 x 5/16 screws actually helps them to fit a bit tighter in the old worn screw holes.
This thread has been quiet of late, so I'm glad to see you join the discussion, Jon.
I took my two #1 original models out for some test shots with both B&W and color film, shooting a roll of each type in each camera . . . it is at the lab now. More when I get the prints back.