With a bit of modelling skill you can make the Carnosaur AND the Troglodon, just make the Carny then model the Trog in water, link, in coming. Edit: Link http://www.lustria-online.com/threads/troglodon-conversion.14723/
I actually have 2 units or three rippers. I wanted to mess around with them and see how they do. The boards my friends and I usually play in are littered with terrain.. lots of funnels... "murders holes" all that kind of good stuff.. So offense can definitely be key here as well..
I think rippers lend themselves perfectly to defensive armies if you run the formation. Blot toads are great for area denial. Also, you can drop the rippers in to your own lines if your priority units are in trouble, or flank an aggressive army that wants to rush your defensive position.
They work very well also for offensive armies. You strike hard in the first turn a sensible target that can threaten your advancing main force (long distance shooters or similar)