My previous post in this thread on the effect of the governor on the whole issue of LFE / LTE is more magnified than usual in the Gazelle, thanks to the wonderful governor.
My experience has been that the tighter the RPM control that the governor has, the more pronounced the effect that yawing has on rotor RPM (and height control in a hover) - a governor that keeps the rotor RPM very close to the datum will react more strongly than one that sort of keeps the rotor RPM more or less perhaps maybe constant.
One manufacturer had to get a modification to their FADEC to overcome the problem of tight rotor (or N2 if you're really anal) control when they went through translational lift and the sudden change in drag on the rotor due to the change inflow made the governor decrease fuel flow quite markedly. Change in governor gain stopped them from plummeting to the ground.
The Gazelle has a very good governor- uses engine oil pressure as the 'medium' to sense changes, and reacts quickly to changes in power to keep the single-spool engine at the datum speed. If you start yawing quickly to the left, the governor senses the rotor speed is too high, and cuts back on the fuel. 60 degrees per second is not unusual, and that relates to 10RPM. Can't remember the Gazelles rotor RPM in actual RPM, but 10RPM is significant enough that the governor would sense it. So, without doing anything to the collective, you'd descend.
But one of the problems is that few people own up to having had a loss of tail rotor effectiveness and fewer bother to report it through official channels (in the civilian world, you'd not be looked on with any favor in your company if you started doing this, for example).
And as previously stated, accident investigators often don't think of this as a possible cause of accidents.
I know that the H-500 early series are notoriously lacking in the T/R department (we have one...)