A little more follow-up:
I went out with the 11x14 yesterday and shot a couple of sheets of film with two different configurations
1. Front element only - this has a focal lengh of 646mm and as expected, covers with more room than I could possibly use. I used it on a shot where I had significant front tilt and about 5 inches of front rise. The resulting negative is very sharp - right into the corners (which makes me very happy because I just sold my 600mm Fuji C).
2. Front and Front elements - this has a focal lengh of 368mm. On one negative, I had a significant front tilt and 3-4 inches of front rise - razor sharp right into the corners. I know that this combination covers 12x20 with a little wiggle too, so perhaps it's time to loose the venerable 355 G Claron.
This confirms for me that this lens has excellent potential for ULF - especially for 11x14 (or 7x17) shooters looking to loose some weight from their gear. I intend combining my twin set of XVas with a 240mm graphic Kowa and that will provide focal lenghs of 240mm, 311mm, 368mm, 476mm and 646mm.