Normally that would probably work, but in this case I've got it pixel mapped to my on screen projector mix. I'll have to see if I can activate another mix off screen and have it use my projector mix as it's source layer. If I had the ability to plug a LCD into the other output this would probably be easier. It's a little difficult when your mac pro is flown on the batten with the projectors!
Thanks for the tip about the mix intensity, that's definitely going into my toolbox.
-Landy