I have a Chrome Kremlin that I used as a messenger for a while. It was superbly comfortable on the bike, but completely uncomfortable off of it. They are great bags, but I definitely would not use one for LS. YMMV.
I'm up in the air about what kind of bag to use. I have a North Face Firewire backpack that has a padded section for a laptop, but it may not have enough room for books.