FYI, my review on HWC has been updated.

THE MCW60 WILL NOT CLEANLY INSTALL!!!!!!!!!!! I have it and a Danger Den Maze 5 here now to test my theory and I can confirm that they will not install cleanly since the mounting holes are about 2-3mm off from the 2-hole retention bracket.

IMO, the HR-03 Rev.A fit because it has a greater tolerance for the holes on its mounting plate.