If you are performing live and want to appear better than others
, then using professional backing tracks is a good option. It gives you an extra edge to thicken up the sound.
Whether you are in an original band or tribute band, tracks will help you to enhance the quality of performance by playing the right track at the right time during a live show. There are times, when your song requires multiple instruments but you don't have enough musicians to play all the instruments, so you can use backing tracks as an alternative to fill the space with it.
It is an art to play the tracks at the right time so that it doesn't look odd to the listeners present on the show. If you are using it in a right manner, then listeners would not even notice the presence of tracks along with the other live instruments and the end result will be admirable. If you have placed the midi files at the right place to fill the gap between two instruments, it will naturally make the song sound better.
Using backing tracks on stage may not be ethically right but if you are using it on some parts like vocal harmony or two, then it won't make much difference and one will get the right song sound. It will help your band to have more recognition and positive response from the audience.
If you have to perform on the stage show, you must consider these tracks as an option which will help you to stand out from the rest.