No wasn't me, but that's a great time! I know, I've been practicing with the Spitter thanks to one of the challenges, and you can really kick some ass!
Edit - I think with a lot of the higher-level unlocks, the game has been getting frustrating as hell for many. Some of the better teams I've seen really start using the gimmicks, like the stun rounds, and there's another underbarrel attachment for the pump shotgun which has managed to kill me in one hit.. not sure what it is though maybe a flechette round?
The spitter's rupture ability is very difficult to counter, and allows for a 1-to-1 kill ratio even if you nerf your attack most of the time. You have to be very coordinated to survive an Escape or Survivor if the Aliens go spitters, which they always eventually will.
Speed is one of the best options for the Aliens, though I fight some who are just incredibly tough, and I dont exactly know how. I can put Heavy Chitin, Bloodlust or Regeneration, and Adrenaline Rush on my soldier and it still gets taken down pretty fast. On the other hand, I'll put an entire magazine of PR into a rushing warrior, and they manage to back me into a corner and hack me up almost every time. I have to bear down on one from a ways away to actually kill it with only the pulse rifle, and this is even using the Accelerated rounds or whatever.
If you are getting frustrated, pay attention to what you're getting killed with and try and use different loadouts and tactics. There are a lot of tricks you can use. The special weapons on the levels are devestating, too, and a marine team with a Smartgun, Flamethrower, and RPG can hold off tons of Aliens if they play right. The flamethrower is just ridiculous, but not op imo.
PS - Try using Escape with your Alien on an outside level. Is both hilarious and perfect for getting you out of shituations.