Have you tried baking an ambient occlusion map with your diffuse map? It will help alot. Also you could increase the normalmap strength on some details of your models, like the gun. Have you tried crazybump? Good high poly models by the way.
The presentation app will only do so much, Serp. It's not a magic "make awesome" method to use UDk or marmoset. I feel most of the props could benefit from a better specmap (seems very uniform, like there is barely any contrast in the specmaps). Same with your dirt/grunge in the diffuse: a bit uniform on many of the props.…