Lee, this is standard behavior. Yes, the voice itself should sustain, but the effects, volume (if programmed to change when you select a new voice) and panning, reverb, etc. will change. Add to that that, if an insert effect on the voice changes during patch change, you'll often get a glitch in the sound output.

You CAN hear this on a G70, if you select the MFX link to Tone in the Options (selects the MFX for each sound as you select them) on quite a lot of patch changes. You'll also hear some quite clear jumps in volume and effects, etc., on sustaining notes if a new patch is selected by the OTS or by changing UPG's.

I am surprised you never noticed this before. Are you sure you aren't subjecting the Audya to higher standards of scrutiny than you have before..?

Don't panic! Don't take a leaf out of Tony's book by screaming 'BUG!' before you have fully investigated the problem...