That’s not a bad idea, especially using a momentary footswitch, so I don’t have to worry about physically fading something in/out. I just need to set up bindings to reroute from sound A to sound B and back again. I’m going to give it a go.
I think the reason I tend to have split zones for that, even just 5-6 keys somewhere at one end of the keyboard is historic, dating back to when I didn’t have the flexibility of Cantabile, and using a split was my only option.
On the other hand, the audience sometimes like to see something happening - there’s a certain charm with those keyboard players of old with 10 keyboards, diving between them, or stretching to play two distant keyboards. Crazy from a performance quality point of view, but fun to watch. So maybe if I reach up 2 octaves to play something, it might make someone in the audience think, “Oh…he is doing something after all!”