Futaba is the only make of RX that still does the "high/low band" thing. But there are differences inside the RX with the way futaba tunes it. So, if you put a "low band" crystal in to a "high band" RX or vice versa, there will be some loss of range. However, the big question is, will the range reduction be enough to notice in our typical "looks about right" "walk away from the model" range checks, and will it show up in the air.

I can certainly believe that while the range would be reduced, I can image it not being reduced enough to notice in the "real world" at least for some guys.

So, I personally wouldn't do it. (Of course, I personally wouldn't buy Futaba RX's for just this reason). However, if you want to do it, do a range check. If the range check works out fine, then you're good to go, and shouldn't have any trouble.

Oh, I'm not sure, but it's alos possible that you might be more open to outside or adjacent channel interferance. That won't show up in a range check, but could be messy later on. I'm just guessing on that though.