To the question of "how can someone -get- to 700xp without becoming game breaking?" I've found the answer is -lots- of skills. Lots and lots of skills.
It takes 75xp to get to rank 5 in a skill and, if the player is ignoring their specialization trees, they can get rank 5 in ten skills while still only having 2s and 3s in their stats.
-This- character is not generally game breaking.
Were the XP applied differently, with more of a focus on specializations, dedication and attributes, they'd be much more of a challenge to the rule system.