I like your list.
If you wanted to drop 90pts I would suggest: Drop the prime off of the trygon as well as 5 termagants from each brood.
You already seem solid on synapse to the only things the prime will give you is +leadership...which you dont need, a few more bolterish shots, and in their face shadow in the warp. I think you can loose this easily.
I like the idea of two alpha warriors with your warrior broods instead of the swarm lord. The swarm lord is really bad ass, but with out guards I dont think he has any chance of causing the havoc you would like. Two 95 point alpha warriors also saves you 90 points.
Everything else seems balanced, fun, and significantly tough.