Genestealers

Use gaunts to tie up the enemy in close combat, then smash into them with genestealers. And, as always, use terrain to your advantage when you can.

I've played games where I've infiltrated too close to the enemy and I've been shot to pieces, but that happens. Genestealers won't survive every battle, but they are still worth it. I wouldn't advise infiltrating or deep striking any unit unless it can get support in a turn or two.

unit04 has it right stealers are worth it but dont cut them off from your army.. so times i will find somegood cover and camp then for a round or two and just make some nice jucie guants near by to shot at. i have found the upgrades on them not worth the points. i havnt tried scything talons yet but i kinda dont want to try, if i like it that is a whole lot of conversions.

XG

Ive also found that if you put one or two in a spot where they can be shot, preferably behind some sort of cover, they will draw heavy bolter devastator or normal squads fire away from everything else. I dont like getting 'em shot up, but it is only a couple. Also sything talons are good on genestealers as they increase the chance of getting a 6 by half.

Lets just put it this way.
I use a g'stealer equivalent weapon for my deamon prince, and if I'm not mistaking the g'stealers have like 6 in WS, right?
When you first get into CC, there should be little or nothing capable of stopping them, no matter what the armour.
Maybe they cost a bit, but that's just worth it.
Just make sure to hug the terrain and really surprize your enemy.

Well, if you have your opponent shooting at the genestealers, then he's not shooting at your hive tyrant, or carnifexes. If he's not shooting at those, then they're going to get into melee with his stuff, which will win you the game. If they don't shoot at the genestealers, then your genestealers will get into melee.

So you have a distraction that is potentially destructive.