I don't know what qualifies as Balanced, but I do have some feedback.
I would probably run 2 guards.
1st there is no reason to ever have 2
BS +
LW on a flyrant. You get the same benefits having one, and a set of Scything Talons. A 2nd is just purely wasted points.
A Dakka Flyrant is soo much better. By going Melee you gain 1 attack in close combat. But, on the turn you charge with a dakka flyrant, you essentially get 11 extra attacks from shooting. Also, in turns you aren't charging, you can still take the shots. A
BS/
LW has some benefits (Instant Death), but I find it difficult to make it worth it.
BS/
LW works great on warriors or Tyranid Prime. On flyrant I would pass, but many people disagree. If you do want to run a
CC oriented flyrant, a few ideas you might consider are Adrenal Glands to make sure you make the charge. Toxin Sacs to reroll failures to wound. The Reaper of Obliterax gives all sorts of benefits, but costs a lot.
With the swarmlord, you don't need Zoeys as much. He has great Synapse, and with 3 psychic powers will likely take dominion. Also your Tervigon is Synapse. I would drop them for something else like biovores.
I'm not a fan of Tervigons, but they do have their uses. Consider outflanking him use "Hive Commander" on the flyrant.
If you are taking Raveners, a squad of Shrikes can be invaluable. They are almost as good in Assault, and almost as fast, and they provide synapse for the Raveners.
Electroshock Grubs is a bad choice for Tfex. He is slow, and won't be able to close on vehicles. I would suggest Shredder Beetles instead.
If you are interested in building a list based on Raveners, check out DuctVader's list:
http://www.dakkadakka.com/dakkaforum/posts/list/580517.page