Well, Thick, that would look pretty badass (as long as it went down to the feet like that model), but the big thing about the model I posted was that it was heraldic. not the design on it. I also really like those shoulderpads. Adds a very lordly touch.
Although that IS someone else's model, so meh.
A surcoat on vanilla plate would still look pretty kickass. Think you could put heraldry on it? There was a PDF tutorial on it by Jik. Over my head but you could probably make sense of it.
Edit: Here it is. Search for the heraldic section: http://www.freewebs.com/jikbyond/40kTut/M&B%20Module%20System%20Doc2-3.pdf
Edit 2: If you're able to put a surcoat model onto the plate, perhaps you could take the shoulder parts from the cuir boille, recolor/texture them and slap those on? It's better than nothing.