As Lady Minion mentions, I have been very lucky with my puffer community and the individual personalities of the fish in there. I would recomend that if you are going to attempt any type of "community" tank with puffers you always keep a spare tank cycled and ready for relocation in the case of aggression troubles. My community has been working for a couple years so far, but with the estimated life span of most puffer species, 2 years is a drop in the bucket, and I would not consider this mix a success for a few more years yet. As I keep multiple tanks (as well as a spare cycled tank) I am able to relocate multiple fish at a moments notice or I probably wouldn't have risked trying to build my little Pufferville.
That being said, if you are going to attempt a mixed tank, South American puffers (Colomesus asellus) are a good choice IMO to mix with the Dwarves, and if you could find them (not too common anymore) Leopard puffers (Tetraodon schoutedeni) are reported to be one of the less nippy FW puffers......but be very sure of your ID before purchasing "Leopard puffers" from the LFS, as they often mis-identify GSP's as Leopards and these are totally unsuitable for FW tanks and usually more aggressive towards tankmates.
