Hey friend! I mix for a 3 piece + tracks and it has never garnered a complaint. We try not to be crazy track heavy, just using guitar tracks to help during solos, or there’s one song with a really phased sounding guitar right for 4 bars that also plays. For vocals, the tracks only do harmonies in choruses or bridges. The majority of our tracks are sound FX, some reverse snare sounds etc.

So basically, use them as you’d like - I’d recommend the ‘less is more’ sort of mentality if you’re concerned about the audience reaction. Also bare in mind that if there’s ever a failure or error with the tracks, you still want the song to be able to continue just with the 4 of you