Square Enix has re-released almost every PsOne Final Fantasy game on PlayStation Network in Japan. Final Fantasy IV and VI are left, but Cecil is about to be stuck on the Solitary Island because Final Fantasy VI is confirmed for Game Archives in Japan.
The PsOne version has two full motion video sequences, a bestiary to read, and pre-battle animations to mask loading times. I imagine Final Fantasy VI will be a bit speedier as a file on a Memory Stick or PS3 hard drive. Relm’s sketch bug is fixed in the PsOne version, but the evade stat (and blindness) is still useless. The Vanish/Doom trick is alive and well too so you can defeat Deathgaze the first time you meet him.