I've built several R1 V16 17.5s and 21.5s, both with and without the 1750 rotor.
When I built the first motor with the 1750 rotor I noticed the squeak when the motor was about to start on the dyno.
The same motor with the original rotor did not squeak as loud and none with a 12.3 rotor.
The 1750 rotors read in the range 1680-1700gauss in my facts machine 2.
The regular rotors I've tested read 1490-1525 gauss. That is quite a big difference.
The rotor being so strong takes more throttle input to start the motor and in my opinion is what making the lound motor sound.