I've been pretty lucky with neons, I only had 2 die for unknown reasons, the remaining 12 are doing quite well going on six months now. I don't know the lifespan, but they seem to be healthy.
From experience once they are acclimated they are very hardy. I have about 10-12 Cardinals and a few Neons (5??). They are over 3years old.
Ps--I would always do a water change before adding any fish.
Give it a try first before you jump to conclusions. Just because it did not work for others, it doesn't mean you won't have luck either.I often think about getting my old 29 out of the basement and firing it up for a school of neons, then I read things like this. :headshake2: