I wonder what it does in the marginal situation of the low RRPM warning just triggering intermittently which is not an uncommon event for a fully loaded robbie and its narrow power bandwidth.
One could save themselves a few dollars and learn to simply lead all manoeuvres with the RRPM, even a more powerful engine would help if the rubber bands can handle it, however because the robbie has become a popular helicopter I'm sure this device will save the lives of those that are more about show than substance.