Mr Marvellous and I did two stalker now we only got them to lvl 10 i belive that was becuase as you point out whoever takes the alpah usualy ended up with a face full of concrete.
They may get better but up to lvl 10 they dont work well.
We have recently rerolled Mr as a stalker and myslef as a dark/Therm Corrupter trhat works better but im healing constantly.
hmmm back in the beta me and my bro tried this out and it worked quite well I can't remember the main builds but I was Energy/Energy and no idea what my bro was ... we got to 12 before the end and like I said was fine but you have to know how to play one or you will be in debt for awhile 
... if in the same room it helps both set off AS at the same time, hopefully not only one person gets all the aggro
i got my stalker to 40 paired with another stalker the whole time and it does take alot of tactics which makes it alot of fun, but yeah it can be done and is fun to boot. 
Defiant's GoEH/MILITIS METUS
I'm currently lvling a stalker with my mate Fen, also a stalker, and having great fun. the alpha strikes aren't too much trouble as we both AS any boss/li at the same time and take them out quickly. Working so far. I'd say to try it, it is difficult, but very fun because of the tactics you get to devise for it (i like playing squishies) ... (and yes, stalker is squishy despite defence, the low hits are squishable)
The Stalker game changes a lot when you get Placate too, so the experience up to level 10 really isnt descriptive for the rest of the game.
Two good stalkers working well together can be awsome in both PvE and PvP, but two idiot stalkers working poorly togheter is probably a lot worse than, say, two idiot brutes not cooperating.
Made a new alt last night, Claws/SR and teamed with a mate who was Claws/Regen and we owned. Claws is such a quick set that you can destroy pretty much any mob between you in minutes. The MM we had was pretty much left getting free XP
Minutes? MM for free exp? whatever for?
Find a decent Stalker. Group up, hit your favorite "Defeat X and guards" mission. Stealth all the way to the boss. Instakill him with doubleAS+placate+extra AS or other attacks. Proceed to splatter the rest of the guards.
5-10min. tops per mission.
Stalkers are awsome!
Our group of 4 (2 stalkers, 1 corr, 1 dom) levelled ok to the late 20s without too many problems, with me and the wife (corr/stalker) teaming with one or both of the other two.
The two stalker team worked ok (em/regen & nin/nin),both dom/stalker combos worked very well, the corr/nin team worked well, and the dom/corr team worked ok. The best duo was either stalker and the dominator, the best trio was fairly evenly split between 2*stalker + 1 dom and 1* stalker, 1* dom, 1* corr.
Then in the late 20s we added a couple of brutes as well, and the levels really started to fly
Providing you go for scrappery type stalkers (em or claws is probably best for this) you should be ok to duo (perhaps recruiting a corr/dom for elite boss debuffery/mezzing as needed). I have a sneaking suspicion that a dark/nin and em/regen duo would be very good come I7 (the dark/nin providing additional "control", while the em/regen mops up)
Basically, how well would this work out? To date, I only have experience with being solo as a Stalker.
My girlfriend is playing an MA/SR Stalker, and I intend to either go with a Claw/Energy Stalker, or Energy/Inv Brute. A Brute and a Stalker I have experience with, but how would two Stalkers work out? With nobody there to really diffuse the alpha strike from the larger spawns, how would we survive in - say - kill all missions?
Hopefully I've made any sense. Any input would be greatly appreciated.