[popo]

B&H pre-order price US$549 which puts it near enough the same as the Canon non-L equivalent which would also gain you AF. On paper spec they're also pretty similar with a MFD of 1ft giving 1x magnification. The Samyang has a more complex optical construction. If that translates to a tangible improvement in image quality remains to be seen, but in general most dedicated macro lenses are pretty good already.

 

At least in the Canon world, I'm don't see any compelling reason to pick it unless you want it as a MF Cine lens. Ok, to be fair you don't really need AF so much on macro, but still other AF lenses might keep the door open for more distant uses.