Does anyone have any opinions on the Booq Powersleeve? I'd like a sleeve for my new PB...but since I'm going to drop at least $30 for a decent one...I'd like some more functionality out of it. I'd like something to take to the cafe or library without my bookbag. So having that strap seemed nice. How does it fit in a bookbag when I need it to? Any opinions on this or any of the booq boa bags? Thanks!