don't like the feeling of the weight on the bike. Everyday I have to carry my laptop, clothes, and lunch but I've gotten used to the backpack and don't mind the sweat to much. I'm looking into getting a Chrome Messenger Pack because it'd work a little better than the backpack I use now, and it'd be waterproof.
Carrying a back pack makes me appreciate the weekend leisure rides more, also I'm pretty fast without 10lbs with me.