A few factors I came to realize after being caught in a slide a few weeks ago.
#1: The face down thing FREAKED me out at first. I thought it was a negative & didn't like the idea of my face being in the snow.
That said, in reality I was under till I pulled the cord & then moved to the top (face down), when I stopped my head was under a little bit of snow. Had I been face up, that snow would have been in my mouth & nose, being face down allowed gravity to pull the snow down instead of dropping it in my mouth.
#2: TWO BAGS. After being drug along rocks under the slide (tore me up a bit) I realize that the chance of the bags being popped is relatively significant. I'm very happy that I have two of them with that in mind.
#3: What saved my life was the ability to swim. Had I been sitting face up on my back I feel that I would not have been able to effect my own rescue like I did. I also am not sure that with a snowpulse I would be able to swim in the manner that I did. The manner in which the snowpulse deploys, seems to m,e would make it tough to swim, even if you were in an ideal position to swim. I also just barely caught sight of the bush I swam toward, and feel that visibility is pretty key.
As a kayaker, I think of a slide somewhat being like whitewater. Being on top is good, but you need to get your AZZ moving toward self rescue. There are rocks & trees all over the place, even if you're on top... you NEED to avoid the oncoming trauma that these items can bring.
Two days after my incident, snowbigdeal had a new canister & trigger at my door... pretty easy & pretty darn cheap. If it costing $20 less to be in a slide is a big factor for you... you should really cut back a bit!
Based on my experience, my choice would be ABS, BCA, AVI-VEST, then snowpulse. I like the snowpulse bag, but do not at ALL like how it works. This order was pretty different before the slide, and instead of having some vague ideas of how things would work & figuring that any of them would BASICALLY do the same thing... now I'm much more opinionated about WHY I prefer the ABS.
Kaleb
edit:
Hey, one thing I should mention... I wear a Leatt (neck) brace, so I don't need(as much anyhow) the head protection offered by the snowpulse. IF you ride without a helmet... I think the snowpulse is a totally different story.