What is, and what isn't DIR?

[grim reefer]

I wear my backplate and harness with doubles all the time and do some great dives with my buddy. But when I teach scuba I can't wear that rig since I am not qualified to teach it.

Wow, Thats a new one. Does your buddy have you thinking you cant wear that rig while teaching? Just wear the damn thing!
I don't see how it violates PADI standards.
What, If one of your studenst show up with a BP/wing your gonna tell him he can't wear it cause your not qualified to teach him how to use it. Thats BS!

Your buddy is violating rule number one when he dives with you j/k

BTW, why isn't a dual-isolation manifold with primary reg and back up reg on the other post a 'reliable independant air supply'?

It is a reliable air supply, But it's not independant if it has a manifold.

I think he was referring to sidemount, wich is safer if diving solo in tight caves.