I managed to get a basic paint job done on the ships from the previous post. The material seems to take Gesso and paint quite well, and I didn't experience any adherence issues. Because of the "grain" problem, I didn't do any drybrushing, in case the grain showed up even worse than before, but I will probably do a wash eventually.
The Dyna-Soar shuttles from the front. They look quite nice, and the grains are not noticeable unless you put your eyes very close to the miniatures.
The side and back of the Dyna-Soars.
The painted Orion ship and the two little corvettes. The grains are still somewhat visible on the larger ship, but again, only if you look too hard.
The back of the same ships. I really like the metallic look that the Orion push plate ended up with. The truss structure of the MOL corvettes didn't turn out badly either, even though they are solid rather than hollow inside.
A size comparison between the MOL corvette and a Kuan Yin class ship from Attack Vector Tactical. Sorry about the bare metal, it doesn't photograph well. You can see the difference between 3D-printed and metal models here. Metal can have much thinner structures.
Overall, it seems the Shapeways miniatures are perfectly fine for gaming purposes. I think I'll definitely get more of them.