Yep. Played GS3 live. It was rock solid, and sounded GREAT.
It was no big show, just a jam session at a friend's house, but I went with 100% Giga from my keyboard.
I set up various patches with split keyboards and Larry Seyer's Big and Beefy Acoustic Drums, SI's Fender P-Bass and the Vintaudio C7. I only wish I had more arms.
For portability I was playing through 200W into a single EV 12" speaker. The drums and bass sounded really punchy and clean. The piano sounded okay, but is much better on my full range stereo system.
Everything went great. I'll do this again. The only difficulties were that I plugged my Midisport into a different USB connector and it took a minute to sort that out, and I had to set my keyboard not to send patch changes when I selected the different setups. I ran with no mixer, so I had to be careful not to do anything to max the volume and send a 200W square wave into the speaker. I was careful, and the cone is still in the basket.
GS3.04 has been totally solid for me. I'll do this again, only I'll come prepared with some sequences, so I can just play piano and let the PC play drums and bass. Some songs (covers) have horn parts, so I can add those too.
The operation was a success.