There is some testing data that the factory did 2 years ago. It's basic stuff, G force reduction, etc.
Info is here:
Here is a high speed camera test deployment (you can see the millisecond counter in the upper right if you watch in HD):
The concern about landing on the Co2 cartridge is certainly valid, I have wondered (worried) about this myself. Personally I feel that if you land on the keybox with enough force to cause injury, you are going to continue to roll and in which case I would want the protection of the airbag system. We have had no reports of injury due to landing on the Co2 mechanism (though there's not enough data yet.)
Spaceharrier, I'm not sure I understand your question about landing on the bag.
Regarding the tether/vs. technology question, cost is a huge concern. If these vests cost $3000 would anyone buy one (I know I wouldn't). Also, I'm still not convinced that I want a computer deciding if I had crashed or not. The tether system is elegantly simple. Yes, if you aren't separated from the bike, it won't deploy but I have to think that it is quite rare to crash and stay on the bike.
Almost every crash report we have gotten, the rider has commented on how secure he felt that his neck was supported. AFM racer Alan Cunningham crashed last year at Infineon and landed on his head while wearing one of our vests and is convinced that, had he not been wearing it, he would been in the hospital. Here is a picture of the incident:
I will be the first to admit that an airbag vest (like any piece of safety gear) will not help in every accident but I am totally convinced that they to do help mitigate the risk.