The basis of your argument is that a diver will be "more used to" breathing off an emergency second stage than using an AIR 2 in a real emergency. I think this is a weak argument for several reasons.. First, a normal diver is going to be grabing and operating his AIR 2 SEVERAL times during EVERY dive (inflate and possibly deflate with it). Utilization of the device is unavoidable.
OK, I don't have one, so I'll assume that you are right about this. But it sounds as if you are just referring to using it as a standard inflate/dump for the BC, not sure why you would be breathing off it routinely several times during every dive? Or do you mean you would just be holding it during the dive to adjust buoyancy? If so, not sure how that translates to practice sharing air.
But then again, it doesn't sound like you need much practice to deploy it for yourself... seems pretty simple to do. Is it just as easy to inflate and dump air from the BC during ascent, while you are breathing from it? Don't know, wouldn't think so, but I'll take your word if you say so...
Conversely, a normal diver is NOT going to be locating and utilizing his back up "standard" second stage several times during ever dive. Not to mention, so damn many of them have them positioned TERRIBLY and all too often packed with sand and mud.. Another safety advantage (I forgot).
Agree with you here - I hate having an octopus clipped off somewhere in the "triangle". They tend to pop out and drag on the reef. I don't use that approach, but many people do, especially with rental gear.
In general, I would go to my Air 2, monitor my air supply and keep the pony bottle for a real emergency.
Wait, you also have three second stages? Pony, primary and octopus?
I have had only a few out of air emergencies when diving. I don't think the presence or absense of the AIR 2 was relevant.
OK, lets hear about those!
As for the video, not sure what it PROVES, but it does SHOW that using Air 2 and sharing a primary is easy. I just thought it would be a cool sequence to capture with the GOpro on an extension pole. If you want to see a REAL out of air emergency on video, I can show that one too, although things didn't go quite so smoothly...LOL
Now we are getting somewhere...! Data! Bring it...