I'm with Mac in that the DMP-7 was the first digital mixer I ever touched. Usable live, but only 8 channels. Still, the motorized faders were COOL.
I knew the future of mixing was in digital comsoles in the early 90's, although few of my contemporaries seemed ready to embrace it. in fact, I tried using a Yamaha 02r as a live desk when they came out, although it was certainly not designed to be used live. If they hadn't doubled up the solo button with the channel mute, I might have kept using it as it was otherwise very usable live. But having to use the channel on/off to cue something during a show just wigged me out too much. Used the 03d when it came out as a small live desk as well. Again, not its primary design function, but it worked.
(As an aside, I'm still using 2 Yamaha 02Rs at my church for Post Production. pretty old school, but They still work just fine. Yamaha knows how to build stuff to LAST.)
The PM1D is the first large format digital desk that i know of that was actually designed specifically for live sound use, although Innovason was an early player in the game. I think their live desk may have come out before the PM1D, but they were pretty scarce in the states so I never saw one. The Harrison ShowConsole was also in at about that time, but wasn't truly a digital desk. It was digitally controlled analog.
The Soundcraft 328 got used live when they first came out, notably here in the Washington DC area at the Wolf Trap center for the arts . One catastrophic crash mid show put an end to that experiment.
I'd love to hear from some of our folks from outside the states to see if there were some offerings there that we never saw over here.