Hunter Dartpipe Chameleons are basically a variant of traditional Chameleon Skinks, but they have an alpha (so they can issue commands) and a 3+ to wound. It is a little repetitive and 20pts more (135pts).
However, if they are truly not visible while in cover, it reads like the enemy can't see them... at all. Which means they can't be targeted by shooting, melee or spells. If you can keep a unit on/in cover, within 16" of the enemy that could be a great harassing unit.
IF that's how it works, that would probably be a bit too powerful for regular Skinks.
Terrawings are a neat support unit that is relatively cheap. The teleport feature while with Hunters seems a little "off theme" for a flying screeching unit (other than they come in a box set together), but that's a nice perk. Reminds me a little of Gryphhounds or Aetherwings. Personally, their ability will be tough to pull off as I play against SBGL and SCE mostly. Occasionally, Khorne player and Orks player show.