Green-Spotted Puffer, not Figure-8. They are entirely different. For one, a Figure-8 would be dead after an attempt at acclimating to full salt. Green-Spotted Puffers can be acclimated because they basically are saltwater fish that sometimes roam into brackish/fresh. Figure-8 are freshwater/brackish fish (it gets complicated on which to truly define them as). Now that that nit-picking is out of the way... :lolspin:
I have tried it a couple times but always ran into other problems that ended the idea. You can try thepufferforum.com if you want to see a lot of experience on it. Last time I visited there was a whole thread on GSPs in saltwater tanks.
The thing to remember about GSPs...they are killers. It is small now. It can't do a whole lot of damage. But it is entirely designed to kill. It must break shells to survive. You can avoid dentistry work by giving them a lot of crunchy foods. Shrimp, mussels, freshwater snails (except Trumpet Snails), etc. These will all wear down that beak a bit. Just about everything in the tank is fair game. Just about everything you listed for your reef tank is part of the GSP's menu. Whether yours will ever realize that will be very hard to predict. Some of them are perfect angels. Some are nice when young and not-so-nice when older. And some are homicidal maniacs. It is really entirely up to the personality of the puffer.