Rob, You sure did a great job on the drawings and stuff!
If my comments "ruined your day" you need to sit down and take a deap breath and maybe a beer. NOTHING I say, or anyone else should do that to you. Just as stroking you for your work shouldn't make your day.
Listen, the drawing you did is pretty interesting and really should work pretty good a trapping moisture. I have never seen it done like that and was taken aback when I first opened it not being able to figure out what it was you did. But after figuring it out, it is pretty interesting.
As for the black pipe, you may have done all the research in the world but you didn't go to any paint gun people. A good volume of high quality air is much more important when painting than running air tools, sand blasting or what ever. Sooooo, I am going to go with what the manufacturers who spend zillions of dollars researching have to say. And they ALL say use galvanized pipe or copper.
I piped my garage with about $50.00 in pipe, all brand new at a retail hardware store. I don't feel that is too much to spend for such a long lasting tool. The diagram, that is from one of the largest paint gun manufacturers in the world. And if you look up the Devilbiss, SATA, and other paint gun manufacturers you will see a VERY similar guideline to pipe your compressor for the ultimate quality air. You will also see that black pipe will NEVER be suggested, in fact they say stay away from it.
This is a forum of discussion and darn it, discussion is good.