Overclasses don't break it by much though. I tested it with my Mathilda (who had max stats in almost everything). Her stat caps in her overclass are
ATK 41, TEC 41, SPD 42, LUC 43, DEF 41. HP stayed the same at 52.
Also Gold Knights overclass has a Movement of 10 (lol). Celica gets a new spell which should be Aura and Alm gets Bow Range +1.