Well, as mdm suggests, exposure times for separations would likely be much less. Using CMB's target of 1.24 logD for the black UltraStable tissues would probably mean at least 2 stops (if not 3) less exposure that what I did. So for separations, you're right about the trade-offs, pre-sensitized definitely wins. But I'd also like to use pre-sensitized tissues for B&W work, as well. In this case, sitting around for 20 minutes waiting for something to print is a bit of a PITA.
I plan on making a test of the other sample eventually. It was similar enough to what mdm used, that I wanted to try the other one first. I only get little bits of time here and there over the summer, so it might be a while before I get a chance. I hope to get more time once the fall settles in.