if you look at this metal; http://www.caponeart.com/SLS_Gow_Trunk_01.jpg
You can clearly see the damaged metal near the big edges that draw our attention. The green metal rust is brown colored, and there are several tones of grey and green in the texture.
The grey and green color of that texture is still in 'range' of eachother but you can clearly see the difference between the different parts of the model.
I think ur dark green and grey are too close to eachother. If you were too look from a distance there probably won't be any difference. Some work in the texture will really improve this model. Also try to keep in mind how ur texture would react with a specular to show off the details