That's great for me to hear as well, about the DT prints. I guess it's a case where "less stable" is still pretty damn stable.

Here's some quantitative info from page 4,

"Even though all types of color prints are subject to light fading, grouping every type of color print together and stating simply that "all colors fade" ignores the very large differences in dye stability among currently available products. Some materials are much more stable than others. As shown by UltraStable Permanent Color prints and Polaroid Permanent-Color prints, it is possible to make color prints with high-stability color pigments that, in a practical sense, do not fade at all: that is, under normal conditions of display, the prints will probably retain excellent quality color images for five hundred years or more."

Charles Berger developed the Polaroid Permanent Color Print process as well, which I believe has nothing to do with dye-diffusion like most polaroid materials, but is basically the same as UltraStable(?). I'd be interested to know the differences.