bugdevheli:
IIRC, blades chopping the tail boom off is related more closely to RRPM, not necessarily low G, and not AUM.
If an instructor doesn't react quickly enough if the stude pushes, then low G will be the first problem to contend with. It's only if the subsequent reactions are wrong that mast bumping will become an issue.
As part of certification, testing of critical flight conditions is done at max AUW - check the H/V curve as an example, and in cases where it's relevant a delay time is built in. If testing in this area was required for certification, then theoretically the situation should be recoverable relatively easily. However I think the only testing done in low-G was after certification to determine the most effective recovery. In short, I'm not sure your theory is a reasonable assumption, but my thinking isn't clear enough to be able to write it down.
Help, anyone ?