Here's my two cents. First of all, I think it's always helpful if you post some of the tactics you are planning on using when playing it. Sometimes when we read it, we just don't have the same vision as you. Now On to actual thoughts about the list.
I think the Belial and Libby combo will be one you see a lot. People used it before, and I see little reason to stop with the new codex. I am a little curious as to where you see the Libby going in the list. I assume you are choosing div so that you can get the reroll to hit's power. Solid Hq choices though.
I agree with Monkey on mixing the load out on the deathwing. I just don't think you are going to need that many th/ss in this edition, especially in the 10 man unit. I can make an argument for and against the 10 man unit. I say play it and see what feels the best to you. I actually think the dev's with las cannons make since, because they aren't that high in this codex. Put the Libby in there and odds are you could get a hit on a flier, or burn down some ground armor. I don't know that you need the full squad of ten, but having some extras for taking wounds makes sense.
I'm against the predator. It's the only piece of armor in the list, and I think you could do more with those points elsewhere. It does generate a lot of dakka, but ideally so will your dev banner. I'd look to insert a different tool in its place.
One other item to contemplate would be a couple drop pods. You wouldn't have to use them, but they could add flexibility against the right opponent. Against a heavy dakka list, you'd get gunned down while you walked across the board. Only, the termies would give you that element at the moment.