While I do agree they are not for everyone and probably most do not have the right sized tanks for them, when I was importing them, I found that ones from different locations had different results. The longer they would be in a bag, the worse they did in the tank. Being in FL, I found that the ones I got from Hawaii were the best for me and they frequently were eating flake foods the day after arrival. The ones I got from places like Bali or Manila however did poorly. Conversely, my customers in Europe had better success with the ones from Bali than they did from Hawaii.
So I don't think you are going to get "new" information that is going to change that result. It's a tough fish to keep because it's more a schooling fish than a solitary one when smaller and aggressive toward it's own when large. Their diet is complex and should include a variety of foods as gut contents included multiple food types including meat and sponge and vegetable matter. So they are not really a "One food fits all" fish.
Next issue is tank size. These are swimmers and need a lot of room for swimming. They also need good areas to hide as well so only larger longer tanks are going to have the better results long term.
Being that the OP is located in Hawaii, I can only assume his success with his Idols is because their travel time had to be short. People further away may not have that same success.