RICHinNC once bubbled...
Pug...
I found your comment about keeping the pony bottle valve shut off extremely interesting.
I USED to always leave it off. The main reason was my regulator would free flow quite often and with only 13 cuft...not good.
When my local dive shop (and dive instructor) found out I did that he went berserk saying I was going to kill myself and people have come to me and said he was telling people not to dive with me because I was an unsafe diver. ((He also has a problem with the kevlar gloves I wear....but I think it is just because I didnt buy them from him))
This may be part of the problem with some folks just straping on a pony. When we carry a stage or decompression bottle it is as pug said charged and turned off. The reg is banded to the bottle and maybe out of view (stowed neatly and out of the way). Having the tank off does a couple of things for us. First, it prevents gas loss. Having the valve off also helps make sure switching to that tank a deliberate act. With multiple regs from multiple tanks it wouldn't be hard to be mistaken about which one your breathing from. The procedure for switching gas/regs ensures we have the right one.