Interesting discussion.
I dive with an AP Valves Autoair on my Buddy Commando BCD. It's a ruggedly built
alternate inflator/alternate deflator/alternate regulator
(click on the auto-air link) attached via corrugated hose to the stab which allows me to breathe from the dive cylinder or, failing that, from the stab or, failing that, from the mini-cylinder attached to the stab.
I have used it in anger on only one occasion, when my own (new) primary reg malfunctioned at 30+ metres and it served perfectly.
Breathing from it at this depth was no more difficult from breathing from my ATX 200, and buoyancy was controlled via my pull dump valves (I never use the Autoair for buoyancy control anyway, since it's not a non-return valve).
Tha Autoair gives me great peace of mind and eliminates the need for an extra hose, though I agree with Mike Ferrara in that I don't think the latter on its own is a particularly good reason for going this route.
Some of my dive club buddies dive Autoair, some dive octo: I don't know that there's a right way and a wrong way. As long as you have a back-up system for emergencies you are comfortable with - and which you know is going to work in an emergency and which your buddy is familiar with - then surely that's what counts?
In relation to MD's points with the Air2 (or any alternate combo):
1. They can be problematic when ascending if sharing air. Not a big deal as it can be done, just needs practice.
You answer this point: practice. Nobody should be diving with octo without practice either, though in both cases they do.
2. You need a long inflator hose on your BC to allow you enough room to bend the reg around to use it. Not a good thing IMO.
All I can tell you is that my inflator hose is no longer than any of my buddies' who dive without Autoair and with octopus. It works in practice OOA air sessions and worked for me in a real-life situation.
3. People forget they are regulators and do not care for them properly. Then they freeflow and cause problems. Not a good thing.
Same thing applies to the octopus option, though I accept that there is probably probably a better chance of octos being serviced at the same time as the primary reg. It comes back to your first point about people's casual attitude to the one piece of kit that could save their lives or the lives of their buddies.
I don't advocate one system over any other. I'm just posting my own experience of this one system.
* edited to add - I should have said that the most important thing in relation to this system is that the Autoair is attached to both the dive cylinder and a
completely redundant mini-cylinder supply, both at the same time. An octopus would not give me this option without carrying a pony cylinder. I'm not saying the jack-booted scuba police should force everyone to dive this way, just that this system has real benefits.
ut:
