I don't like Kady or Katy or Katie. They're all just icky-sweet little-kid-in-cough-medicine-commericals. Kady has the added disadvantage of being spelled kre8yvleigh, and as you say, it sounds the same as Katie, so it would be just another in the slew of Katies already running around. If you want to be different from all the other Katies, choose a different. name.