Well, it's been a year and I thought I'd give an update on my A/C system. What I did was posted here:
http://www.subaru-svx.net/forum/showthread.php?t=27636
Anyway, the Duracool (R12a) stuff has been working great. I had a very slow leak and during the late spring I noticed I wasn't getting into the 30's degree range anymore. I could get into the low 40's, but I wasn't getting in the 30's anymore, or if I was, it didn't last long.
So I added some more Duracool. Probably about half a can. Well, that ended up being way to much. Over the course of a couple of weeks, I'd let out a little bit here and there. Drive it a couple of hours and see where it's at.
I've noticed how to tell when I've got to much in there. If I'm driving a steady 50 mph, and it's getting into the 30's, but when I'm on the highway, it goes up into the 40's or 50's, I have too much in there. So hook up the gauges and let out a pound, and try it again.
Duracool and the other R12a variants, are very sensitive to the amount you have installed and can easily have to much installed because you don't need nearly as much as R12 or R134a.
So I took a little 1 hour trip on Saturday along the highway, and my A/C got down to 26 degrees. It's only gotten 26 degrees one other time, so I think it's running perfectly right now.
For those that want to know my pressures, I'm running about 29 psi on the low side, and about 195 psi on the high side. This is doing the test running the engine at 1700 rpm for 5 minutes when it's hotter than 85 degrees out.
After looking at R134a, and the other R12a variants, I think it's a no brainer to choose the R12a stuff such as Duracool.
Hopefully this well help those who have A/C systems that are only blowing tepid air.