Sorry, but as I have made it well known, I'm an anti-MP3 advocate. But I'm also NOT a DJ either. I'm a professional sound enigneer.
Don't insult your clients by offering them a reduced quality experience for your selfish convenience.
If you want to cut back on media, convert your CD's to 16-bit 44.1 PCM WAV files and lug them around on a hard drive or memory sticks with NO LOSS in quality but easier access. Or, convert to DVD with a simple menu system and "label cards". You should be able to get almost a 4:1 ratio with no quality loss.
I'm old school. I may be stubborn but I refuse to give my clients "LESS" so I can be convenienced. MP3 is not an acceptable format at any rate. I refuse to work on a project from initial concept through tracking, mixdown, mastering and mass production and then onto touring. Why make an effort to knock the quality down at any step along the way?
I'm going to be making myself some "long play" audio-oriented DVD's soon, just in case I need longer background music. Sort of a set and forget at low volume thing. In my case, it's all about the band.