I guess it all depends on how you look at it. If you want to please the masses, then Stand Back is in. Probably most casual fans don't know or even distinguish between Stevie's solo song and Fleetwood Mac songs. I personally never liked the live version of Stand Back very much. Also, I know when I go to a Fleetwood Mac show that I am only going to get 6-8 Stevie songs, so I sure in the heck do NOT want one of them to be Stand Back.
I personally love Fireflies and think that it would be such an appropriate song for this tour.
My two cents.
Kevin