ORIGINAL: RCKen
Jose,<div> ok, I've read the document you supplied three times now but nowhere on it does it say that the end user cannot change out the crystal in their transmitter. It does speak about them going to more narrow frequencies, but it doesn't say anything about the end user not being able to make the switch themselves. </div>
That document references the applicable U.K. ruling documents on radio regulations that unfortunately address this in more technical terms.
Aside from all of that, the same problems exist with their bands vis-a-vis crystal changes affecting sideband spikes, power output, bleed, etc.