I work with a drummer and deliberately include a rhythm track, with usually the high hat and snare panned hard right so that he gets that out of his monitor (we just send the stereo PA feed to our monitors; I get left and he gets right).

When we first started using midi files / style in support of our sound we would "lose sync" very often. These days it is a very rare occurrence. We think this is due to 2 main things: familiarity with the songs and mainly being able to play the tunes to an exact tempo.