I had an AT IMC and, before I had him, I thought it was overpowered too. After I had it, I can say its power depends on the campaign. I mean, if you plan to start from 15th level, and you run a city campaign (where SA is always possible and infiltration is always the best way) it is overpowered, simply because that is the point of the Trickster.
In a normal campaign, where you find all the types of creatures you can imagine, and you start from low level, it's balanced. You don't have a Wizard and a Rogue, you have a multiclass character that enters a PrC at 10th level (after Rog4/Wiz5 I guess), that is less focused (and powerful in combat) than any other character 'till level 12/13, where he begin to be a real Trickster. Moreover, your AT is a Rogue that uses Wizzy spells to help himself -a lot, ok-, but not the master of metamagic or the DC Focused Wizzy, that can be done only by a single class spellcaster -who has only one stat to raise, and doesn't need to enter melee combat or even stay within 30 feet-.
So, no, it's not broken..