STV Deep femoral is still going to take only a few seconds. yes some people have been lucky. But as more evidence comes up with clotting products, it seems they are not the miracle everyone thought. Its a 1% chance product. Does it work? yes. Will I ever buy it... probably not. Right now the conflicts in Iraq and Afganistan are teaching us huge amounts about trauma medicine, we've already seen tourniquets come back into use with better guidelines than before. As more of that info filters down, we will be able to apply those lessons learned. Obviously it takes some time to mine data from very chaotic situations. If you want to carry it, that is entirely up to you.
Bob, you've got mostly right. Recovery chance drops 10% for every minute the heart is stopped. compressions extend that out, and even with no added oxygen, as long as the heart is moving, you've got more time. Basically when the heart stops you are dead. There are times when the heart can re-start itself, but very rarely. And most of the medical conditions that stop the heart are shockable. So getting the shock there fast is critical, and as more defibs are available to the public, we are finding that more and more often people are getting treatment within a couple minutes, and having good outcomes. O2 can extend that time as well, but it makes little difference in the first few minutes, and if those are wasted, the dudes a gonner anyhow.
Another CPR aside, a couple studies have shown that the best CPR you will ever preform is the first time. That adrenaline rush gets everything going hard and fast. The worst are old ER docs, they have to act dignified, don't get panicky, and so don't push hard enough. As my mom puts it, if ribs aren't cracking, your not trying!
Sorry for the derail, just trying to help clear things up, since its been a thing I've had to put a reasonable amount of professional time into.