Well, I know your room mate is looking for a larger bird, but Our little yellow sided Green Cheek conure is to die for! He's so well socialized and so far get's along with everyone, even people he's never met.
Our conure has the personality of a larger parrot and get's along well with our 2 tiels. Each of our birds have their own cage and only are together during supervised play time. Mostly our conure just wants to climb all over us and could care less about our tiels.
I think it COULD work having your room mate get a bird, the biggest thing is to get a bird that is well socialized and KEEP him/her socialized to different people so that when your room mate is gone and the bird is in your care, he/she would have less chance of bonding specifically to you.
HOWEVER! Keep in mind that with birds of any species...you just never know, they sometimes will bond to one specific person no matter what you do to try and keep him or her social. And often times bonded birds to one person become agressive to anyone else in the room. If this should happen to your room mates bird and it's NOT your room mate that this potential bird bonds to, what then? Another re-homed bird? It's something to think about. I tend to think that larger birds have more of a tendency to become 1 person birds...and because their bite is bigger and ouchier, this can be a very bad thing.
Anyway, under the circumstances I think a Green Cheek Conure is a good choice. I'm extremely partial to them now that one owns us.

They are relatively quiet, and especially quiet compared to a larger parrot and their acrobatic skills are amazing! Quite comical characters.
BTW: We are a family of 5, plus all our kids friends who regularly socialize with our birds. And currently my husbands sister and her 2 kids are living with us...UGH! Makes for a packed house (8 of us) but very well socialized birds
Good Luck!
Toni