I've just fitted a pair of Shimano BR-M445 disc brakes to a bike I'm building up for my partner. They're cheap, non-series components (although appear on quite a few pre-built bikes) and rather chunky and workman-like in their construction. The rotors too are thick compared to my XT ones.
The combination of extra chunky calipers with particularly wide mounts and thick rotors means that with the rotor centered in the caliper the rotor passes within a fraction of a mm of the edge of the lower caliper mount. In fact at the rear it was initially catching the edge of the mount.
I've now got reasonable centering of the rotors and clearance from the rotor, albeit tight, and as the calipers are done up nice an tight I doubt they'll shift but, for the future, would there be any harm in filing down the edges of the mounts?
no, but if they don't foul, no need.