Thud,
As you know, and have obviously shown your friend, the Limitiations section of the B212 RFM says...
Rotor RPM Power On, Min 97%, Max 100%
Rotor RPM Power Off, Min 91%, Max 104.5%
There should be no further discussion. Furthermore, the old 204 / 205 habit of drooping the rotor to get more power doesn't work on the 212 (or the 205 with 212 blades for that matter). The 212 rotor works best at 100% Nr, and loses efficiency below that number power on.
If your friend would like something a little more official, that can be arranged as well.....straight from the horse's mouth so to speak.
