Hi Michael,
I did make a mistake. The program I was refering to is BobCad and it doesnt read in the colors.

The reason (and mistake) I made with MoI was I did a test and didnt think it was writing the colors in.

My test was a cube and I gave each of the faces a color and exported, then brought it back in and the cube was the default color! I thought it was not writing colors.

On further review, since you showed it is, I recreated the cube with colors. As seperate surfaces, the cube exports out and back in with all the colors. If I join it back to a solid, then export and import back in, the cubes entire color is that of the ground plane color! (apparently in my tests, that must have been the face I left at the default color) So on import, the entire cube was the default color.

Anyway, if I leave the surfaces seperate, the colors are going back and forth.