I have at least a few of all the cars mentioned above - - except the PRR GRa gondola. As a PRR modeler, I would buy at least a few. If you are referring to the Weaver woodside gon - IT WAS NOT A PRR GRa however they painted it. Among the errors, the major one was that it is 2 scale feet TOO SHORT - which is noticable. Also Weaver did that car with cast on detail, which compared to the more detailed stuff I have been migrating to, it does not stand up well. I do have 6 of the H30 covered hoppers and Weaver did a great job on them. I have a pair of the Milw cars too, but how many rib sides can a non milwaukee layout have? I also have all the Atlas cars mentioned.
As for the SW from Atlas - it is a very nice loco, I have two.
I wonder as I read this and comment if the market is a bit saturated - especially with generic stuff. Modelers are getting more knowledgeable and want models that represent specific prototypes in my opinion.