I can confirm my feeling regarding the different signals coming out of the receiver for 3ms (fast) and 1,5 ms (utrafast) speeds. I used a skyrc programming card to mesure the reciever ppm with the following results:

for normal signal down to 6ms
Signal frequency: 165 Hz
Left:1105 uSec
Midpoint: 1507 uSec
Right: 1909 uSec

for Fast and Utrafast:
Signal friquency: 331 Hz
Left: 130 uSec
Midpoint: 300 uSec
Right: 472 uSec


So obviously Fast and Utrafast will not work for equipment expecting standard (1500 uSec) signal modulation.

It is a question how one finds equipment for Fast and Ultrafast signal as most of the time there is no specifications available for the accepted ppm.