Well, I bought an SA puffer couple of weeks ago. He/she is currently with my apisto and seems to be doing well. The apistos stays at the bottom and the puff, well rules the tank. So far no real incidence of aggression from the puff but the apisto do and are currently taking care of eggs so they stay within their territory.
My puff eats frozen (thawed) bloodworms, mysis shrimps, krill, and snails BUT his favourite meal is the NLS pellets. He would eat the pellets before touching anything else. I guess that is a bonus since the pellets are somewhat "crunchy" and hopefully keep his teeth in check. I will use a bigger size pellet as he grows. Right now he tiny...maybe one inch and I can see him take the pellet and bite a few times before managing to break it apart. Sometimes after a few tries he would give up on the pellet and grab another pellet.