My guess would be either subtle damage on the other areas or none at all and using a BD head and chest, that way you can market it to more than just folks interested in a BD version.
IM DX is probably going to be around $200 without shipping and tax, this package would have to be very appealing to sell for that price, are people with the clean Mark 3 going to drop $200 just for battle damage? However, they might go after an improved figure that can be clean and battle damaged and more.
My take on DX is that the figures made in it are able to offer variety in looks, Joker has 2 costumes, Batman has gear for his various looks in the film, Iron Man being able to be clean and damaged would be fitting.