I also managed to get all the bases completely stripped so I can burn through them all at once. Damon, one of my favoritest Adepti-Friends suggested green on the bases back in 2012, and I think I'm going to take it one step further by emphasizing a warm/cold contrast.
Ahnighito's Zigouilliers: bases in progress
I'm starting the dirt a deep red-brown and working up a couple different shades of blue-green. I couldn't get the colors in the pic to ring quite true enough, but they look a bit like oxidized dirt under moonlight. I still need to add detailing - dingy/rusty metals to the gears/girders, green-tinged grey to the rock and concrete, and neutral metals on the shell casings. It sounds odd, but I'm hoping the end result brightens the Iron Warriors a little and contrasts the minis in a way that helps the hazard stripes pop.
As usual, updates as progress warrants.