I assume that you are lookng at Coral Morphologic zoas? I have always had good luck with Florida zoas. Many people say that they melt but for me they have done just as good as all other zoas if kept in healthy conditions.
Many of the Fl zoas have sponge growing with them. As long as you get the zoas that are free of sponge or have been collected properly they will be fine. Only ones I have had problems with are those with sponge and as the sponge dies off in the collection, transport/shipping container it tends to harm the zoas.