Yeah, I think the listing Paly is not what most people think Paly's are. Palythoa's take sand into their coenenchyme (stalks), so they look kind of sand papery. Zoanthus do not (smooth staolks or mats). Size of the polyp has nothing to do with Genus, though it can be a rough indicator. The standard Protopalythoa psammacora (which will likely be absorbed into the Palythoa Genus sometime in the somewhat near future) is the typical Palythoa, but most call large zoas Paly's.
1. That said, I have a lot more Zoanthus than Palythoas (probably 50-60 different morphs of Zoanthus and 3-6 morphs of Palythoas). There aren't too many Palythoas out there (PD's, green buttons/Protopalythoa psammaphila, and some others that are similar to those growth characteristics including Proto grandis).
2. There just aren't as many Palythoa sp. offered compared to Zoanthus.
3. The Palythoa sp. I've had have been bullet proof (Protopaly psammaphilla specifically-or one that looks pretty much identical to the commonly accepted Proto psammaphilla) . I've had them for over eight years now, while others seems to wax and wane. The Rabbitfish that took out 8 colonies in 2 days didn't touch any Z. gigantus or Palythoa sp., so I would assume they either don't taste as good or have more toxin.
4. Just options.
5.I've had pox, unexplained melting (probably chop-shopped or something like that), and a rabid Scibbled Rabbitfish that took a seat at the zoa buffet (only the nice ones, though, then it moved on to my Acan lords and echinatas and micro's).
6. Increased water changes and temperature control worked for me on the pox on multiple occassions. Stopped buying from people who were known or suspected of chop shopping. Removed the Rabbit.