I'm late to the discussion, but here's a point or two that hasn't been mentioned yet:

When deciding on a delivery method for backing tracks, the simplest answer depends on what functionality you need.

For example:

1) if you just want background music to play along with, the simplest delivery system is an MP3 player. (in all of these cases, I assume you will be sending output to an amp or PA system)

2) if you need to see sheet music, lyrics or other visual cues, you'll benefit from a device with a screen.. either an IPAD or a notebook computer

3) if you want to control lights, MIDI devices in synch with the music, then you'll need to play the song from sequencing software such as RealBand, Sonar, etc. Because the MIDI commands needed to control external devices can be embedded in the sequence file. This also requires a notebook or IPAD in conjunction with sequencing software.

Of course, even if you only need music to play along with, you can still use the device that is capable of more functionality. That way if you want to add functionality later, you will already have your set list in sequence files.

The nice thing about using an MP3 player is that they are cheap and you can always have a complete backup in your other pocket in case the first one dies.

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0