Leigh, regrading your post #19: Do you know of evidence of a pushover in this case?
I don't know this model of gyro but, in general, the contemporary Euro-pod gyros (all with Magni-ish tail groups) are extremely resistant to, if not immune from, uncommanded pushovers and drag-overs. To be sure, most of them have some degree of high thrustline and low center of drag, creating the POTENTIAL for uncommanded nose-over excursions. The large H-stabs typical of the breed go a long way to making this a remote possibility, however.
There is the possibility of an intentional forward stick input, perhaps by an aggressive pilot (of the personality type described here). There is disgracefully little systematic research about exactly what the consequences of this may be. We do know that, In a craft that relies on its rotor thrust for stability in pitch or roll, there can be an uncommanded pitchover or rollover during low-G flight. With an adequate H-stab, we eliminate the pitchover risk, but we don't necessarily eliminate the rollover. The latter can be caused either by a hard side-slip in a craft with a low body pod or other low-placed draggy item, and/or reaction torque from the prop.
Persistent low-G flight may allow the rotor to lose enough RRPM so that it experiences retreating-blade stall when the load is reapplied. A flight condition of this sort is not easy to achieve: The craft has to follow a ballistic trajectory, with the rotor disk at or about zero disk AOA, long enough for RRPM to decay significantly. An intentional entry into an outside loop, with considerable airspeed, comes to mind.