Finished this guy today, and I really can't say enough good things about the model. Awesome sculpt and a ton of fun to work on.
My thing at the moment is figuring out ways to combine airbrush and hand brushing techniques reliably, and it worked out pretty well here. The basis for the two skin tones is burnt umber with a zenithal spray and then I did a wash and tightened everything up with regular layering/edge highlighting on the flesh tones and drybrushing on the grey. Next I'll try this method on the King of War from Creature Caster, should be a good bit more difficult what with all the clutter.