I know this is going to sound silly, but why do divers wear their tanks with the valves on top? Firemen wear the valves on the bottom, where they are MUCH easier to reach. Granted, the hose routing is simpler with the valve and first stage up top, but it seems to me that a bottom mounted first stage would facilitate a hose routing similar to the DIR "under the light canister" position, then under the knife, around the back, etc. It also seems that a bottom mounted first stage would be less likely to snag, and easier to clear if it does snag. (and easier to turn on in the event that you forget!) Am I missing something?