Charla's tears may have just been a ploy to make it look like she really didn't want to get rid of Toni, but she had to to stay in the game. I can't imagine that Charla would really be afraid that Keith would choose Toni over her after Toni berated him the night he kicked Zack out. Or maybe she was just overwhelmed at the pressure of being the leader of the Outsider Alliance, and therefore the main target (along with Keith) of Toni and her gang.
I didn't like Charla much at first either. I thought she was a stuck-up bitch. But after getting to know the others in the "hotel", I can understand why Charla said they're all "childish". Apparently they think they're still in high school. But now that there are a few others that aren't fooled by the adolescent antics of the Inner Circle, Charla could afford to be bolder and make her play to establish her own alliance to offset the IC.
Beau's a tough one to call. I thought he was cool at first, but ever since that Amanda/Alex episode, he's been going downhill. I thought he had FINALLY wisened up that he's not one of Toni's gang anymore, but then he threw his lot back in with them last night. He's too wishy-washy. Amy picked him because "Zack trusted Beau the most", yet Zack told Keith that he wanted Alex and Scott to stay. He didn't say anything about Beau. Someone needs to tell DJ Boy that he's fresh out of friends.
Charla played her hand perfectly. She took a risk in testing Tara's true loyalties, and Tara passed (this time. Will she next time?). Once that was done, it was an easy choice to eliminate Toni.
I think Amy and Kristin are powerless now without their Burly Protector. The balance of power has shifted... for now.