I think the perspective the problem. The concept art does look awesome, but it's probably the angle you see it from when firing it that makes it not as cool looking.
I still love the flat, exhaust emitting Unreal ASMD the best, but the '04 one is a close second. The two barrel look, one for each fire is slick. The Unreal version was more fitting to the time. It's designe kind of had you wondering what the heck it even did before you fired it, and that was fitting since few even know all what it did until quite late in Unreal's life.