If you mean 1:1 macro, the 1.6x effect on DoF doesn't apply. The DoF is deeper on APS-C results from being further away to match framing (or using a different focal length). At 1:1, you're at the MFD of the lens, so no change in distance. In that case, the DoF is actually (very slightly) shallower
Take the example of a 100mm Macro lens shooting a coin at the minimum focus distance for the lens (i.e. 1:1 image magnification).
The FF will give you a larger FoV at 1:1 magnification. On APS-C, an Indian head gold dollar
(a coin smaller than a dime) at 1:1 will just fill the frame. On FF, that gold coin will not come close to filling the frame, but you could put a Canadian quarter next to that little gold coin and still fit both in the frame at 1:1.
OTOH, with current sensors, the APS-C will put more pixels on target, meaning the same object photographed at 1:1 on both would look bigger at 100% on the monitor in the APS-C image. For the same pixel-level magnification, you'll be further away with APS-C, and have deeper DoF (but that wouldn't be the case, for example, comparing the 5DII to the 20D, since they have the same pixel pitch).