I have already posted on the Carbon Forum, but I'll put this here also as a high-power alternative for alternative printing.
I actually use the 450W equivilent, with carbon printing exposure times of around an hour for non-staining developed negs. I don't mind the hour exposure times -- I can work with two different negs at a time. While one is being transferred and then developed, another neg is being exposed. And these lights are cheap enough to get two seperate systems going and that would keep one constantly working...no waiting for a tissue to be done exposing. I would not use the 450W for anything over 8x10 -- the 750W might work well with larger negs than that.
I personally would not use a bank of BL (or BLB) tubes for carbon printing -- the diffuse light would soften the image far too much for my taste -- I want carbon prints as sharp as the negative.