Yes I thought the surly fork was a rear FM style, rather than a front FM style. Looks like the FM caliper would bolt straight to the fork for a 140mm disc, and the adaptor in the pic is for 160mm. I am very undecided on the dropout thing - I feel that QR should be fine and give no problems at all, but TA does have advantages... the surly fork in QR version is ISO mount, I think, so easy to adapt to any caliper.