well, I personally thank miss J for those cherry shrimp, wow they were healthy, BTW I've lasted breathing in and out of a breather bag for about 20 minutes, yes they definitely work, so I guess that's why they were so healthy
I think it's strange that you actually experimented that on yourself, though I am glad to hear that they do work.
I've received many shipments of shrimp via breather bag. The only time I got a DOA shipment from a breather bag was when adult tiger shrimp were shipped to me. I was aware that they were adults though, because that was what the person had for sale (he was getting rid of his tigers to make room). I don't think it was completely the bag's fault. A majority would probably be the fact that they are adults and adults don't tend to take shipping too well. A second thing is the water volume in the bag was too little to carry 5 adults + 5 or so juvie RCS.
So here's a tip to people who plan on shipping larger shrimp in breather bags. Make sure you have plenty of water and space in there! Large shrimp will definitely need more room to swim around. If the bag is too cramped up, you will end up stressing them.
I think this is a common mistake done by many shippers using breather bags. The fact that you won't need too much water and no need for air space is a good thing, but they forget that water for a "comfortable" space for the inhabitant is also important.