Here's my issue with the Wardens - not every badass Wizard is, or should be, wearing a Grey cloak. The Warden's are the police/soldiers of the Council, and as such their ability to act outside of that role is very, very limited. We've thus far seen the Council, and the Wardens, largely through the eyes of Harry Dresden, one of the top 20 most powerful spellslingers in the world (by his own estimation). Remember, if many on the Council had their way, his head would be bouncing on the floor in some abandoned warehouse.
Harry is a Warden because it was politically advantageous for him to become one, not because of his great power or skill. Just because your character is powerful doesn't mean the cloak is for them.
Now, the question I have to ask is: does your character owe anything to the Council? Does he feel a kind of deep, abiding respect for the Laws of Magic and the established role of Wizards in society? If the answer is yes, then I say put on the uniform. I would say the same thing to any young person who felt like serving their country was so important to them that they enlist in the military, or that protecting their community was so important to them that they put on a badge and a bulletproof vest.
Keep in mind, though, that many people serve their country and their community in very important ways without ever enlisting or putting on that badge.
Are there other reasons why one joins the Wardens/military/police? Sure, and maybe that works for your character. Regardless of the justification, everyone who wears the uniform has to follow the rules. If following the rules is something your character is about, awesome. But don't think you can jump into the never-never and consort with Summer without many on the Council trying to use you as a pawn.
Personally, I say keep the Cloak off, and create an equally badass NPC Warden who is a sometimes friend/sometimes foe. Just my 2 cents, though.
