I will throw out more questions than answers but here goes.
I shoot four formats above 8 x 10--
10 x 12 which I find to be a perfect marriage between size and portability. Especially in my Wet Plate Collodion work I find this size to have more of a presence than 8 x 10 yet still be very manageable. Film is available if you order when Ilford or on the odd occurrence that Kodak offers a yearly run of film. All of my 8 x 10 lenses worked on the format as well so that was an added bonus.
To the panoramic formats you mentioned choosing from I chose 7 x 17 over both 8 x 20 and 12 x20 for the same portability issue. I travel quite a bit for work and both the 10 x 12 and 7 x 17 can fit in a home configured garment bag that will slide easily into the overhead bin of planes. I didn't feel 8 x 20 or 12 x 20 would do that as easily as often as I travel. Of course anything can be accomplished but for me the 7 x 17 was the best in regard to the ease of constant travel, as I have never been asked to check it etc due to its size. I love having it on the road with me as my down time then becomes a joy instead of more CNN or other mindless road fare. I also love the ability to still be able to view the prints 'in hand' which becomes more difficult as you go up in size. They tend to be wall prints above that to my eye anyway. Having seen prints from both those formats though you could hardly make a bad decision as it basically comes down to your lifestyle etc in regards to how you shoot and process. I'll state the obvious disclaimer here--7 x 17 is easy on the sink, trays, need for new lenses (anything that will cover 11 x 14 will usually work for 7 x 17 as a general statement) etc front as there are many options listed here in the archives. 12 x 20 starts to be a 'lay siege on the mountain' assault full of new trays, more chemicals, maybe even a new sink although there are usually ways around that, lenses to cover the format, darkcloth etc etc. I also ended up getting a 20 x 24 with a 16 x 20 reducing back so I know those waters and all their undertows!! I set my photographic life up for both the travel and when I am home (I shoot the smaller formats when I travel the bigger when home) If I had chosen just one format thought to work with instead of the sickness i seem to have I would go with the bigger format and never look back. When I'm not traveling I love to see one of the big negs coming out of the tray.
Wish I could help with the actual manufacture question but alas I haven't seen those cameras in person. Just wanted to add some of the thoughts I didn't think about as I was thinking of all the joys of bigger formats. I can't say I regret any of it just would have been nice to have thought about all the things involved as I was making some choices.