I've picked up a cheaper box of the Horrek's, and will start messing with them. They look (from the pictures, waiting for my purchase to come) like nice models, just worried how to paint the inner skulls aside from the rest of the horse.
The irritating thing for me is I like the Petrifex faction lore (I love archaeology, so the idea of this faction hunting down fossils to create new warriors seems awesome, plus if I can get some interesting skulls, some nice conversion ideas), but the faction doesn't seem too good now.