in my opinion you dont need to power level. if you dont run you got good level for the dungeon. but you need at least level 60 for fight the end boss for kill him more easier, so if you want to power level wait for the last dungeon ok?!
Playing: PS3: God of War Collection | PSP: Persona 2: IS; Final Fantasy 4: TCC | PC: The Darkness 2; Overlord
Nah if I didn't power level I'd end up with Rosa and PC's before Edge first joins not even at the same level 25 that Edge first joins at.
But since all the good spells for Rydia = level 46 and Rosa level 36 I'd rather just grind Paladin Cecil to that level forcing Rydia Rosa and Kain to ALL rejoin like at level 50 over having to manualy grind them from level 25 to double levels since it takes longer to level with a full party.
Yes level 55 is find for the final boss/ most lunar ruins trials save for maybe Lunar Odin since I couldn't survive its Z sword move even at level 55.