yep that was the same adapter on that m700 on ebay, the seller actually emailed me back to say he'd taken it off an old Gary Fisher. but he said he had to drill the M700 frame in order to clamp it on.
I'm still curious about this A2Z one, and i might just buy one and see if it fits? if not i'll send it back? either that or just run a disc on the front only??