AM steam runs pretty smoothly and you can get decent slow speed response out of them. They all have a Flyer-like piston and smoke unit, which I'll admit is toylike, but there's a switch to turn off the smoke and the whole thing comes out easily.
The drives are bullet-proof. There is a little noise amplified somewhat by the resonance of the boiler, but nothing I find objectionable. We ran a Pacific at an open house for 6 hours straight with no problems.
The USRA Pacifc is a very basic locomotive with solid performance and was AM's first steam locomotive. It doesn't take much to improve their looks. Each succesive steam locomotive became better detailed, although as I mentioned earlier, most of the detail is cast in.
I can post some pictures of a reworked Pacific tonight, but here's a picture of the Northern, also slightly reworked with an MV lens, graphite paint, numberboard decals and crew figures:
There's also a little pixel magic with the sky... This appeared on the cover of the NASG Dispatch a year or two ago.