I think Doug's article on equipping Simon T for an air race is an excellent read, even for non-pilots like myself. The key to ensuring you have the proper survival gear with you in a fast, emergency egress is to wear it. Doug configured Simon's gear to fit in his flight suit and vest, both of which are hopefully leaving the vehicle with him! <img src="images/graemlins/grin.gif" alt="" /> If you are not wearing a flight suit or not flying over water, then wear pants with cargo pockets and hunting or fishing vest to stash your gear. Larger gear can go in a separate bag or container that you grab hold of on exiting the plane, but redundent PSK type of gear on your body helps ensure you have what you need to survive.

BTW, one comment on using a backpack. I use a backpack to lug my laptop and other stuff when I commute. The straps tend to get hung up on thinks (gear shift, etc.). I would imaging you'd want to secure the straps for use in a plane, otherwise it may get stuck and you'd have to make a quick decision to spend time unsnarling it or to leave it.