Today I did a couple of test sheets with the Cooke XVa on 8x10 in every combination. I deliberately shot every sheet close to the edge of the image circle (as close as my camera would allow - I had two inches of shift and about 2 inches of fall where possible) because I would ideally like to use this lens on 11x14 (combined with a 240mm). Two sets of cells provide 5 different focal lenghs. They all cover 11x14 except for the back+back combination which is only usable on 8x10 (273mm focal lengh). The others look like this:
Front and back - 311mm FL just covers 11x14 (can get about an inch of rise at f64)
Back only - 476mm FL - covers 12x20 with quite a bit to spare
Front only - 646mmFL - covers 12x20 with loads to spare
Front and front - 368mm FL - covers 12x20 straight on
The negatives are not yet dry, but I will report back tomorrow when they are and I have had an objective look. However, they appear to be plenty sharp right into the corners...