I've got the ultimate, and after seeing how big that was, i figured the OS must be truly gigantic. Reality does not disapoint. Is there a way to laterally compress the OS?

One issue- you might want to wrap an extra velcro strap around your pump to the strapping on the bottom of the bag. I had some problems with my pump coming loose over bumpy roads, and it sucks to backtrack a couple of miles to find out where you dropped it.