Not having seen your POP prints Joe, can you attain the typical blacks and white that Azo can produce consistently or is the coloration dark purple? The ability to get POP in 11x4 and larger sizes could get me going in this direction. What are you using as a UV light souce? A contact printing frame with springs or a vacuum frame?
Do you have a link to some of your POP prints? I'm also curious about your light source, specifically, have you used a metal halide or mercury vapor bulb?
The colors I do get consitently that match my azo prints are on the greenish side of azo's spectrum, the hue I usually aim for. Again, this is because of the first fixing bath. I mix 240 grams of sodium thiosufite to a liter as a sort of stock solution. For the working solution I'll use 300ml of that to 200ml of water. As it starts to age the colors become more and more vibrant.
After just looking at prints I made last night, there isn't a hint of purple in them. When going into that first fixing bath they had a very dark purple, but after 4 minutes it's gone.
In my post yesterday I said that it'll move through yellow first; I said that backwards. In my experience this how it happens: After a couple seconds in the weak fixer you'll see the typical pop color intensify, then after a couple minutes it'll start to vanish in the lighter tones (and eventually in the darker tones), then green will move into the lighter tones. If you keep going the green will move into the lower tones and you'll start to get yellow in the lighter tones. I can't stress enough that you've go to print heavy.
If I were to put one of my azo prints next to one of my pop prints, color-wise, I doubt one could tell the difference.. d-max, and the depth of the shadows (just glow overall) is another story. Pop's tones, especially the lower ones, are much richer than my azo's tones.
It's also possible to get platinum/palladium print looking colors with expired pop, but I'm not about to go off on that tangent.
I'm using homemade spring back frames. On my 8x10 negatives the prints are just as sharp as prints I've made using a vacume frame (actually sharper, since I develop my film semi-stand now).
As a light source I'm using the sun and blb tubes for less contrast, and open sky or cloudy days or printing in the shade for more contrast. I've never used metal halide or mercury bulbs.
I don't have any prints online that you could look at, but I'll send the two of you some if you give me your mailing address. I'm heading to Italy tonight and won't be back for two weeks, but I'll get them in the mail soon as I return.
There is a draw back to using this paper... no burning/dodging (of course there can be if you have the patience). I look at this as a blessing though, seeing I want to spend as little time in the darkroom as possible.
Michael, I hope you do start going in this direction. I'd love to keep this paper around as long as possible. Can't promise you'll have success right away, I didn't, but I'll give you as many pointers as it takes to get you there. I can promise that you'll have a number of unexpected pleasant suprises though.