Well, I decided to start a new thread on this. I decided to go to REI today with the 8x20 in tow and see if this new pack would work for the 8x20.
I was in Yosemite last weekend for four days and really wanted to get off trail but my rolling case wasn't going to cut it in the snow.
This pack handles my 8x20, two holders, dark cloth ,extension rail, two lenses, my Packard shutter and other odds and ends. I still have the top compartment and side pockets empty. It comes in at 31 lbs. It is lighter or about the same as my 8x10 kit. The 8x10 has more holders.
I figured that 4 sheets of 8x20 is a decent output and I can always go back to the truck for the other two holders and re-load.
My 8x20 fits snugly and this pack may not fit a 12x20 ( if you want me to check my dimensions let me know). I think this would be great for the 7x17. You would have plenty of room.
It lists for $199.00. Right now they are having a 20% off until the end of the month and I used my dividend to bring my cost at just under $100.00.
I'll post some pictures when I can. You can go to REI.com to check it out.

Next: A pack for the 11x14!!!! When will it end???