Lionel has never done a 2 rail engine, so even it close to scale, it is of little use. MTH has, but the flaws mentioned above make it a poor choice for me personally. The red Caboose loco has a nice superstructure, but the mech is lightweight. Atlas got the dies from Red Caboose/Intermountain and have used them, but they use the infamous china block drives.
those two motor drives are good pullers and run well around loops but any I have had are not nearly as good as single motors for an oprating layout that requires switching and slow speeds.
By the way I think possibly MTH and maybe Lionel has done a 3 rail RS3. As for the atlas one, I don't know if it close to scale dimensions or not. A friend of mine had a pair of them. To both of us they looked funny. They looked too tall and so appeared too short. The shell may be right, but they sat too high on the trucks and just did not look right when compared to photos where they appear long and lean.
I guess this sounds like rivet counting, but I don't feel it is. If the model does not "look" right to me from 3 feet away or so on the layout, I don't like it. I do have MTH 2 rail GP30s from years ago in the 90s when MTH did some 2 rail stuff. From "2 feet away" they looked as good, or just like the brass one I had. As a result I sold the brass one.