I cut my teeth mixing sound for musical theatre with a few amateur companies. 2 1/2 days of get-in, room balancing, pit setup, tech rehearsal, band calls, dress rehearsal and the rest. Almost invariably you'd get the comments from some audience members that it was a lot of equipment to use just for playing back a recording. It was quite a compliment, although they didn't realise it at the time...
How we woud laugh when the actors decided to miss a few pages of dialogue and totally mess with the cue list!!
As for what I do when I'm playing, I have enough to worry about making sure I'm playing the right song, never mind obsessing about whether or not the audience appreciate the nuances of my slap-dash tonal choices. By the time it's mixed with the other 6 people in the band, all the audience will ever hear is dum, dum duh dum anyway.