Torquetalk, I agree that in a lot of R44 accidents the cause of the low rrpm horn going off were probably as a result of over-pitching rather than the LTE itself.
Assuming nil (rather than your 40 kt) wind then, could full LTE develop without the horn going off ? Picture the MRs turning anti-clockwise for the R44 and the main fuselage turning clockwise during LTE. Is the MR rrpm not referenced to the fuselage ? As the fuselage is turning the other way (clockwise), the tacho could sense that rrpm is sufficient. However, aerodynamic wise, the MR blades could be turning much slower (even without over-pitching) and this may not be sufficient for continued flight, even though the LTE itself would have the effect of off-loading power from the TR (thus producing more power for MR thereby creating lift).
This is just a theory as I have no figures to back up. Maybe someone out there does.