[e.k.]

Many of our hymnal arrangements have half-step key changes. We usually have multiple guitars, and they often select different capo settings. Some of our guitarists also like to re-voice mid-song at times, e.g. for a final chorus or something. Changing the capo setting using the dialog is nowhere near as fast as a smart button, and painful experience has taught me that having multiple “custom” versions of arrangements leads to confusion. 

How this would work: I have an arrangement that is in B major with a key change to C major for the last verse & chorus. The bass player just uses the ChordPro as-is. One guitarist wants to play in G (capo 4-5), another wants to play in A and change to C (capo 2-0). Each player can use the smart button for a quick one-tap custom capo change, giving them more time to move their capo and keep playing.

This is no more “exotic” than any of the other smart button actions; in fact, it’s exactly the kind of thing smart buttons are for.

@ jlgtx,
since a lot of years, I´m doing arrangements for a group of 5-6 guitar players, 1 bass, 1-2 percussion players.
And, yes, sometimes we have to change key, but never capo (as an example: Three Wheels On My Wagon....key change every verse).
I heard "change capo within a song" the very first time......even it´s technically possible, of course.

IMHO, it´s not a question of mobilesheets, it´s more a question of skills of guitar players.
Just as a hint: Play power chords in such a situation, or for Latin/Jazz shell chords, so you never need any capo (change).
But this leads to far "out of topic" related to mobilesheets.

e.k.