They're interesting devices, for sure. Seems like a sound investment.
Armored textiles and leathers protect you while sliding and knee/shoulder pads provide some impact protection. The air bag products, I would think, would certainly provide more protection on the "impact" side of the equation, such as Wendell's unfortunate experience (assuming they inflate in time).
A bit pricey in my opinion, but not terribly so considering the cost of anything motorcycle related (and likewise for equestrian I'd wager, which they also market it to).
It's like insurance I guess - the more protection you want the more you need to spend. Everyone has their own demarcation point between safety, comfort, cost, and appearance.
Thank you for sharing the review. I'll need to keep an eye on these.