GrumpyOldGuy
Contributor
If a pony bottle is only for yourself.. then why would you need an octopus?
The simple answer is because the octopus is connected to a cylinder with much more capacity than the pony. In addition if you are sharing air with an OOA buddy, you only have one tank to manage as you ascend with the buddy (who has already demonstrated he is a moron).
The problem as I see it is a pony can mean anything from 3cu ft to 40 cu ft, back mounted or slung, with or without a readable SPG. It may be full, 1/2 full. Valve may be on or off. The diver may check it every dive & know it works, or he may just assume it should works cause it did 6 months ago. Is the size adequate for the diver at the depth? or how about the buddy who may have a much higher SAC. All of these needs to be reviewed before one ditches a 2nd stage in an effort to simplify his rig slightly. Its not a simple answer.