Monk,
In your post you say
I merely point out that the point at which TDP is reached coincides with the onset of translational lift.
That may be correct for some Helicopters/Take off profiles, however, it isn't true for all. As an example the Puma L2 (when operated to Cat A) can have a TDP which varies dependant on a number of different factors - take off space available, aircraft weight, temperature etc. I'm not going to go into detail on the calculation, but the TDP can be between 25 and 70 Knots IAS, well in excess of the onset of translational lift.
Brom.