Futaba uses "high or low band" for their receivers. Why? I'm not sure, but I wouldn't risk my plane just to find out. I'd suggest sticking with the appropriate channels.

I may be paranoid, and I don't know where you fly, but if you put that crystal in a high band RX, range check fine and then fly, you are risking losing your plane and possibly hurting someone when your plane decides to come down.

Mike