No way of me knowing your personal story and that you own a company. Not really sure why it seems you are getting defensive because I questioned if you have personal experience with the fish mentioned. Still doesn't say much either way on the other hand... I know of a store that has someone maintain their display tanks. Moving on..
Also, you are right, you didn't say "I've seen" you said "I know" I'm sorry. Still was no way for me to know your experience either way with those fish. Could of been anything from looking at the tanks for 5 minutes to actually owning them yourself. Hence why I asked.
And did what exactly with my Achilles? Properly quarantine it and establish the way the tank is run specifically for the Achilles? I believe plenty more people can keep other Achilles with similar care and thought put forth. My Achilles is not hardy by any stretch either... It was close to death at the LFS, so theoretically it should be dead I guess. I am definitely NOT the "one person" who can do it, you are drastically over-exaggerating.