untreated wood into concrete ~10 to 20 years depending on location &
environment

Around here - rain all the time - I keep hearing 10 years from locals. I'm
planning to be here for longer then that, don't want to have to dig them out
and replace them in 10 years.

A deeper socket would be better but they must have done some tests?????

Maybe, maybe not. It's possible they did some tests and this is the next
best thing since sliced bread. It's also possible they did some preliminary
tests and just dumped the things on the market. So, take a 100 foot run of
fence. Imagine the posts being held by a 4-5 inch tall pinch bracket.
Imagine a 20mph wind blowing. I can just see the entire fence blowing over.

I really like this idea, so I'm researching it to see if it's viable.

buy one or two & do some experiements with them

Yeah, I will probalby do this. I'm hoping someone here has actually used the
things so I don't waste $20-$30 in case they are not useable for a 6 foot
tall fence.