RE: Hi/Lo band
Al he's talking about US channels 35 and 36
Futaba center tunes on the lower or upper half of the band. So if have a low band rx thats center tuned to channel 23, and put a channel 36 crystal in, your 13 channels away from the optimal tuning channel.
If on the other hand you have a center tuned receiver (remember, that Futaba didnt do that on all recievers, just for a couple of years on certain models) like any other reciever out there, including most Futaba 72mhz systems, its tuned to channel 35 (the center of the band) and you can put a channel 59 or 60 crystal in it and it will work just fine, yet its now 23 or 24 channels away from its optimum tuning.
Hence my statement, given the stated circumstances, I seriously doubt he will find himself any worse off than anyone else flying a 72 mhz system. Now if he were going to throw that channel 59 or 60 crystal in it, then you might have a case of saying it's not a good idea.
Like I said, if you're that worried, just have it aligned to the actual channel you're flying on.