List B... Were you refering to the Swarmlord maybe... 280 pts, it sounds like it.
You need to put the Doom in a pod. Players who know what he can do, will take him out quickly with a insta-kill shot. You need to get him in quick to be most effective. Remember that he can affect troops in vehicles with his spirit leech, although they will get a cover save.
Where's the heavies?... not a trygon, mawloc or 'fex to be seen.
On the tervigons, upgrade the stinger salvo with cluster spines. It's a free upgrade and gives you a big pie plate at strength 5 instead of just 4 strength 5 shots.
I'd go with list B. The swarmlord is a nightmare in assaults and with his additional special rules he can be overwelming to opponents. Just don't forget to use his swarm leader ability at the beginning of the shooting phase. You'll also need to shield him or utilize terrain to get him across the board.
That's my 2 cents, hope it helps.