Tyranid 'Drop-Spore' Army Increase to 1850pts

I am due to attend the Caledonian Uprising at Maelstrom in Mansfield in January, and army lists need to be submitted by 22nd December - next Thursday! To say I am in a quandary would be an understatement. The list needs to be 1,850pts, with Special Characters allowed - all to suit the prevalent ETC tournament scene, it would apprear.

The core of the army is largely fixed - I will be taking a modified version of my very own 1,750pt Drop-Spore Tyranid force which I had so much fun with at Blog Wars II which Alex of From the Fang organised and ran last month. The 1,750pt army is as follows:

HQ - Hive Tyrant with Wings & Hive Commander

ELITE - 2 x Zoanthropes in Mycetic Spore
ELITE - 2 x Zoanthropes in Mycetic Spore
ELITE - Doom of Malan'Tai in Mycetic Spore

TROOPS - Tervigon with all the trimmings
TROOPS - 10 x Termagants
TROOPS - Tervigon with all the trimmings
TROOPS - 10 x Termagants

HEAVY - Carnifex with Heavy Venom Cannon & Twin-Linked Devourers with Brain-Leech Worms in Mycetic Spore
HEAVY - Carnifex with Heavy Venom Cannon & Twin-Linked Devourers with Brain-Leech Worms in Mycetic Spore
I have tinkered with the list slightly to remove the Tervigon upgrades I didn't use (ie Onslaught), which leaves me with 120pts to spend. I really want to keep with the deepstriking modus operandi of the army (only the Tervigons start on the table, and only then in objectives-based missions) so I do not want to add any foot-slogging units. The army has a decent firebase, consisting of the 'dakka' (I hate that term!) Carnifexes and the Zoanthropes to deal with tanks, and good anti-infantry capability courtesy of the flying Tyrant and of course Doom. All in all, the army works and I'm afraid to tinker with it!

So, what are my options?

I have thought about adding 8 x Genestealers - they are my favourite model in the whole hobby after all, so they don't need any justification! However a unit of 8 is likely to be dealt with very easily, even if they arrive from reserve via a board edge using Outflank.

the other viable option I have thought of is to add 7 x bases of  tunnel-swarming Ripper Swarms, with Spinefists. They complement the deepstriking theme of the army, are multi-wound troops (ideal for objectives missions), have multiple short-range shooting attacks which may surprise a few folks, and can be used to tar-pit strong opposing units for a turn or two.

So, I need your help!

What would you suggest? Genestealers? Ripper Swarms? Or something else entirely?

All positive comments gratefully received!