For what it's worth, I routinely cycle with my macbook pro in a pannier -- enclosed in a Vyper case, mind you -- and have never had any problems with the hinge or anything else.
I don't take it mountain biking or anything, but I do go down the occasional cobblestone or dirt road. Heck, my pannier even flew off my bike once (thanks to a pothole and my own ineptitude in securing the latch to my bicycle rack), and there was nary a scratch on the computer.