ORIGINAL: Dr1Driver
The 127 is either high band or low band. Also, theoretically, you can change any frequency to any other in the same band. In reality, I like to stay within 2-3 frequencies either side of the original. If I go farther from the original, I send the RX off to be retuned.
Dr.1
While having a reciever tuned is always a good idea, the three channel thing really isn't getting you anywhere. They are tuned from the factory for the center of the entire band (or the upper or lower half in the case of some futaba recievers) and not for the final channel.