It works great !
Using the Bandhelper app on my android tablet, I got my midi device working and am able to create songs, add presets to the songs and add the songs to a setlist.
Each preset sends two program changes, 1 on midi device channel 1 and another on my midi device channel 2. I created 2 midi devices for my single mio midi interface to allow sending on different channels.
When I open up the setlist and the first song, I am able to press the midi icons and send the midi for my preset into my Reaper DAW and I can see the program change pairs coming through.
For testing I set up keys 60 and 59 in Bandhelper remote control to "next preset or song"/"previous preset or song" and using my Reaper virtual keyboard to move forward and backwards through presets.
This works perfectly. I'll be showing my piano player this afternoon and I think he's going to really want this. I assume he can do the same thing in Set List Maker, yes ??
Thanks for the help Arlo !