I agree with taking the Rippers out.
If you decide to keep the tyrant and the carnifex, give them both a second ranged weapon. As Monstrous Creatures, they may fire two ranged weapons during the shooting phase. Besides, considering you'll fight a large number of "shooter" SMurfs, your carnifex will never make it into CC. Also, if you give these two a second ranged weapon, you can drop the Zoanthrope. While the Zoanthrope's ranged attacks might be more tempting, remember they have a much shorter range; so drop it and use the points for additional weapons--specifically for Barbed Stranglers.
Your Warriors: I'd drop the either the rending claws or scything talons in favor of another Deathspitter (best option imho) or another ranged weapon. This will give your Warriors more punch as they make there way toward the enemy.
Troops: So far, if you drop the Scything Talons off your fex, tyrant, and warrior, drop the Zoanthrope and the Rippers, you have gained 115 points. If you pick up the Barbed Strangler for your tyrant & carnifex, Deathspitter for the warrior, you've spent 50 points, leaving you with 65 more points of gaunts to play with. I think 1 brood of Stealers is nice, but i'd spend any additional points on more gaunts; you have the potential to get many more models on the board, and I suggest you do so.
Your Carnifex: You may find the the extra wound from Reinforced Chitin pays off more than Extended Carapace. Considering the low point total (1000), I'm not sure how many AP2 and AP3 weapons you'll face. If you face alot of AP2 weapons, then Extended Carapace is useless, so pick up the extra wound and spend the extra 10 points on Gaunts. If you don't think you'll face many AP2's then it might be worth it. I personally would take Reinforced Chitin regardless, but that's just personal preference.
Anyhow, hope this helps. Good luck.