A long time friend of mine, Peter (Ski) Schwartz toured as the musical director for David Bowie and the Pet Shop Boys in the late '90s. Here's what he had to say in a MacProVideo interview:
“I’ve been involved in two world tours, one as musical director for David Bowie on the 'Outside' tour and also as musical director for the Pet Shop Boys 'Nightlife' tour. Both of those tours involved MIDI rigs to play backing tracks that the bands played on top of. The Pet Shop Boys tour was particularly intensive MIDI-wise because we had a rig of about 20 synths. They recognized the difference between having backing tracks being played from tape or having those sounds played live from synths, because it's never the same twice. So we had this huge rig - two refrigerator sized racks filled with Nords and Roland JV's and all kinds of other stuff. There were also some samplers too, Akai S1000's and 1100’s.”
“I was running upwards of 16 tracks of audio on Logic from a Mac PowerBook and driving a whole bunch of MIDI stuff at the same time. I was the first one to ever use a Mackie D8B on the road. The reason I specified that for the rig were because there were so many synthesizers and the levels from one song to another were going to be all over the place, so rather than programming MIDI volume commands for each synth, I thought it'd be a lot easier to be able to move a physical fader to control the level of the synth outputs for each song. So I had the playback for all these synths and the D8B to mix the song and I would save the mix in a snapshot.”
“On top of playing back all the synth and sampler parts I was also sending program changes to the D8B - it had motorized faders so - from song to song it would switch the mix. And having an actual mixer to control levels made it really easy to make level adjustments during rehearsals and sound checks. It was a pretty extensive rig!”