Alice just proved her ROI lol. When I left work yesterday, I just unplugged her, closed the lid and slipped alice in my backpack. There it sat until getting to work just now—with 2:35 hours remaining on the battery!
This thing is energy efficient enough to take several times my laptops battery life, when under a normal load. Let it go into restrained sleep and it's pretty darn long lived; I have Linux programmed to prefer using more power then is strictly necessary when on battery as well.