Choice 1: I lose ammo like there's no tomorrow. [Carly]
Choice 2: I gain an early warning system. [Doug]
That's a hard choice.
I saved Doug originally because I had a feeling he'd be jury-rigging all sorts of crap, as is the wont of very technically minded sorts. So I just had a hunch that he'd turn out okay.
On the other hand, Carly just isn't very bright. She goes blabbing about Lee's past right away and at an awkward time instead of keeping her peace for a better time, she wastes ammo like there's no tomorrow whilst claiming to be a crack-shot maverick, and she can't handle putting batteries into a radio.
I mean, the intelligent woman on the team is Lilly, and I'll be sure to keep her alive and well. But Carly? Yeahno. I'll take Doug, every time.
Besides, Lilly and Kenny are both plenty good with guns. So having a third is a pointless, ammo-wasting redundancy.