As everything else you do, a great paintjob!
Like the Op, I would let the colour sceme depend on the heraldics of the army.
Personally, I would have used more brass/copper for the armour, but thats just my 'dwarven preference'.
I also would prefer a slightly 'lighter' tone of fur - but then again, I've never painted a mammoth!
Don't take it as critcism, it was just what came to mind at a first glance - as I haven't seen the model 'in the flesh' I couldn't really tell if it looks a bit different under 'normal' daylight or electrical light (I bet it does, my photographs of minis are NEVER quite 'natural').