Metallic models are great for easy paint schemes, I like the look of those, although they are a bit dark. As was mentioned before, washing your metals with inks will give them a more used feel.
I use chestnut or brown ink for golds/bronzes and for silver metals (like boltgun) i use tamiya smoke.
If you wanted to brighten it also, you can highlight just as you would any other model, except with a lighter metallic shade around the plate edges.
Other than that, I like em, especcially the different colored rods. Ive seen entirely too many green rodded necrons.