On Gargoyles: I fail to see the benefit of CC5+ (other than marginal tactical uses, and in those cases, they would get in CC irregardless). The main benefit of Gargoyles is the 45cm FF or the defensive 25cm. My suggestion on Gargoyles (if AA is out of the question) is to drop them to 20 points instead, but keep them as upgrades. Their higher Swarming value as well as being an upgrade would equal things out in my opinion.
With them featuring less and less in our games that's pointing me towards an internal balance/points issue, yes. You're probably right on your last point, but I'd like to represent that they are somewhat better in CC than Termagants thanks to the various biomorphs they've had over the editions. I'd like to start with that, if it doesn't work we'll explore something else/more.
On Swarming: I support D2, or keep Warriors fixed at 1 and Tyrant at 2, Dominatrix at 3 or 4.
We'll try fixed (halving, rounding up, if within 30cm or broken?) if d2s don't lead to a noticeable difference.
On Broodlord included in Swarm as opposed to upgrade: I like it since it pushes a formation out of the crammed 150 pts' option.
Noted. Are you getting an extra attack out of him or is the Leader/Inspiring enough?
On Zoanthrope AA: I think this gives zoans too many uses and takes away a little of "one creature - one use" feel that I think is appropriate for Tyranids. Also, I usually run a small swarm with 4 zoanthropes running between the Dominatrix and my Hierodule for FF protection and support. With the Dominatrix and Zoanthrope AA, this suddenly gives Tyranid a solid ground-based AA, an area in which they should be lacking. Since Zoans are quite a good upgrade in batches (I am thinking of 4 to 8 ) they pack quite an AA punch.
I've got other posters saying Zoanthropes are finally worth taking now. What are the multiple uses you're inferring to for them? AA and FF beast? I haven't tried more than four in any of my games yet, and those four have been spread out across two formations usually.
Dominatrix AA: I think it is relatively fair, but the Dominatrix could use an increase in points.
25 points bump? More?
On a related topic: Are there builds you are concerned about and you would like to see tested?
Harridan spam is still on my chopping block, whether lots of small formations or bigger ones. How have you found Lictors, Genestealers and Trygons? Also, how do Carnifex compare to Malfactors/Horospex for you?