Chas, the sad news is that the customers really don't care what is generating the music. Many assume the arranger is already doing everything automatically.
One time, several years ago, I arrived at a nursing home in another town and found I'd forgotten the keyboard. I did the show singing with midi files from my computer and they never knew the difference. BTW I almost never use "backing tracks" whether MP3 or midi, but that's because I love to actually play.
It's rather sad, but the vast majority of one-man acts around here use midi or karaoke tracks from their pads or phones and play guitar and sing with them.