Jim I was thinking about you this December when we were trying to make B&W slides from TechPan, me and my dad. We had setup a flash unit behind a diffusing plastic screen, and so used it as a uniform light source to shoot the original negatives. However, we forgot to take into account the fact that TP has an EI of about 200 in a paper developer to get the right contrast index (we had assumed something like EI 25). So when the fix is done, I open the tank and give a quick look at the neg to make sure there's something on it before wasting water on the wash, and from a casual glance I see something indeed.
Problem is I did not look at the neg by transparency, but by reflection, and it looked like a normal negative. I was heedless enough not to realize that I should have seen a POSITIVE image, this being a copy from a neg. Once we hanged the TP we saw immediately the error, but it was cool to make a direct negative copy on another negative through solarization. Maybe that could be a new way to copy negs without losing more than one generation...
Sadly, we never managed to make those damn slides, and called it quits after three hours of bracketing, fussing, and trying to reduce the intensity of the flash.