noamraz........ I think bringing another PC rig and recording on to that at the same time is overkill....... and a whole other pile of gear to set up. You won't be able to watch both systems at the same time when there is a lot going on stage. I sort of ride the' faders' when needed although technically they are knobs on the Motu's. I can not say enough about the performance of the Mac and Motu's during sessions......... they honestly have NEVER let me down ( I need to knock on wood now!)
I have a template set up before the show and I give it a trial run at home just to check everything is OK. I come back from the gig and transfer a copy of the session to the G5 and keep the origiinal file on the Glyph HD until I have edited and mixed the session on the G5.
The only thing I have lost is when one of the HDs on the G5 died and I had to replace it ......... I still had the original file on the Glyph so all was well!
I have a PC as well .....but would never ever risk doing a session with it. It's for AutoCad only!
If you were using Motu gear you can give monitor or headphone feeds using CueMix on the from the same system you are recording with.
Good luck
forsooth