If the only issue is the color of the mini, then I have no qualms about proposing the one as an alternate sculpt for the other. And, in fact, when I said that I would like the Knights of Weston to do double-duty, the Knights of Blackgaard were what I was thinking of first. After all, at the highest level of competitive play, repaints are perfectly acceptable.
So, yeah, that's an excellent suggestion.
I'll have to come through later and put all the "live" suggestions in the second post, and see where we are.
edit: Thanks, Bat! I'll have to look later to see if that's comparable to the Azurite Warlord. I think it is, because he's not as tall as he should be, IMHO.