The reason I do this is because my little tool allows me to preprogram a 100+ preset and cuelist before ever even getting to show site. It also allows me to close Catalyst and replicate settings between cues very rapidly.
Granted, I must close Catalyst to use my tool but it's freaking fast.
Welcome to the world of Production.
I've only tried this once but I had a show where I was driving 12 old TVs. I wanted to use Catalyst but only one machine. So I stuck 2 X1900 cards in the machine and tried 4 TH2G boxes. I also tried 2 Quatro FX cards as well.
To put it simply, they just don't work. I even tried hacking the hell out of the core operating system to spoof it into thinking each video card was a single output.
The bottom line is that 2 cards just don't yet work with Catalyst.
Perhaps someday (maybe after Snow Leopard) Richard will integrate support for 2 cards.