While here we worry and complain about the mixer and ipads, there are always a lot of things that can go wrong at a gig. Having 2 keyboards nearly ensures the keyboard player won't be left out of a gig. From that standpoint, trumpet players are unlikely to have problems at a gig. Sax's can need service to get back in playing shape. (Cracked pad or bent valve.) Extra strings will get a guitar back quickly but a broken string isn't the only failure that occurs. (Broken strap pegs will drive you nuts.) That's enough worrying for this year.