The Macro and Micro have the same mount/holder, so I would place the light centrally in the holder. Also, I would be tempted to use a small o-ring (crossing over the top) to secure the light to the holder: it's what I do with my Garmin Dakota GPS. Since the mount is easy enough to remove there's little chance you'd need to take the light out of the holder.
The Micro rear mount does look more likely to jettison the light, and I have heard that this can happen. A zip tie seems like the answer here. Still the Smart R1 is good light, much cheaper and lasts for longer - I can't justify changing it for anything else.