I do.
You're correct in one sense, but not entirely. All air vests as far as I know operate in the same way (I'm not counting the integrated systems from A* and Dainese). You have a tether clipped to the bike, and if you crash the lanyard yanks a trigger and fires a big CO2 cartridge. Basically the exact same mechanism that's been used for airline life vests for decades.
Where you're a bit off base is the design of the vests. There's considerable variability there.
There are two leading manufacturers, Helite and Hit-Air. Hit-Air is somewhat less expensive. It has provision for armor inserts which (I think) are optional and sit between the airbag and your body. The Helite vests have what they call a "turtle armor" concept, which places armor outside of the airbag.
Both manufacturers have street vests and track-oriented vests. Here, Helite is the clear leader. Their track vest is very slick and absolutely disappears when on the bike. This vest, the GP-Air, has a leather shell. All others, including the Hit-Air track vest, are textile.
Since I own a Helite, I know that repacking is super-easy. I don't know about Hit-Air.
The track vests are different from the street versions because you're in a tuck all the time. The street vests, with the bulky canister hanging off the front, get in the way, so they're more suited to riding upright (typical Ninjette riding position). The Hit-Air track vest solves this by putting the CO2 canister on the back. My Helite solves it by burying the canister underneath a smooth armor panel on the chest.
Regarding usability: I've commuted wearing my vest, but I find that it makes using a backpack awkward. There's just that bit of extra bulk. If I weren't wearing a pack, I'd wear it all the time. So for commuting, I've reverted to my Level 2 armor insert. (BTW I no longer wear a back protector on the track... the vest, in between its armor panels and the air bag, serves this function.
The photo shows my vest in use. As you can see, this particular version is so low-profile it doesn't impact riding the bike at all.
I got a live demo of the Helite street vest at last year's motorcycle show, and it was impressive as hell. Held my head like a cervical collar and was very confidence-inspiring.
The big question is cost. My vest is, I think, the most expensive one out there. Still cheaper than the integrated systems from A* and Dainese, but not an inconsiderable investment. You have to decide if it's worth it.
"Investment" is the way I look at this. Even a relatively minor injury like a broken collarbone (one of the more common riding injuries) will cost FAR more than the vest.
