Jill Heinerth has a pretty good how-to video clip about the armadillo sidemount setup for carrying stages. It's on her Rebreather Pro homepage.

I generally jump in the water (when from a boat) with bottles clipped to my harness d-rings 'old-school style', then make the quick switch to the bungee to take advantage of the streamlining. I've found that on the larger bottles where there is a little more swing to them even when affixed to the top clip on the stage hardware, they can stay clipped and swing in close enough to take advantage of the bungee. Generally speaking, being a new england guy with choppy surfaces most of the time, I'm hesitant to jump in unless everyting is clipped in securely with hardware first.