It's been a while since I've touched any GS, though I'm pretty pleased with the carapace - relatively smooth and will look pretty seamless once its painted black. I could have done a better job on the weird part above the head, which is one of those things that comes about through interesting shapes done with the sculpting tool that in hindsight I should have worked on. As it is that area looks too random and unfinished. I'll try add something to it before i prime them (hopefully over the next few days).
I just ordered a tervigon, 3 boxes of warriors, tyrant and some gaunts as well as parts to start converting a prime and 4 hive guard (all of which I'm really looking forward to converting...). I also got some magnets to magnetise the gaunt weapons - fleshborers for tervigon spawned beasties, and devourers for the others, interchangeable; and I hope to be able to remove the scything talons from the carnifexes without damaging the paint-job, so I can magnetise them to swap between devourers and talons. Here's some random pics of the models so far:
and a group shot: