Of all the new contrast paintings my new favourite is not a paint, but what GW calls a "technical": Contrast Medium. It works beautifully with GW inks, better than plain water as it gives you more control and avoids those ugly stain effects and ink-pools that you got simply using water. It has allowed me to paint the six Russian Crimean War models that came with Wargames Illustrated this month in just a painting session (which, for me, is equivalent to lightspeed painting!). And they came out pretty good given the fact that I use a single block colour, the ink+medium and just a light in the face and hands and in the crossbelts. I think that I have some picture of the test model in my phone... It's not great, but it gives you an idea. From start to finish, it took 15 minutes plus some downtime while I waited for the ink to dry.
Almost forgot! For the face I used one of the new contrast paints (Darkoath Flesh! Check it in GW website!) mixed 3:2 with medium over a block colour of Vallejo Base Flesh. The ink I used for the uniform was Agrax Earthshade mixed 1:1 with medium. I primed the miniature with one of the spray primers they have released in its contrast range (can't remember the name, it is a yellowish-white finish); I like it a lot for the smooth surface it gives; it suits pretty well my painting technique (it was 41º degrees in Madrid when I primed the miniatures but the finished surfaces didn't present the rough finish that usually gives white primers in dry, high temperatures)