I'm currently reviewing Avalon Code, and while I like it overall, the whole code management system IS a pain. Being stuck with four slots makes juggling codes a necessity, and it's tough because you don't always know what code you need when. Oh! I need that "Fire" code that I just did something with an hour ago. Now where the heck did I put that?
I'm hoping that as I progress in the game, there'll be some kind of upgrade to improve your code management system (double its capacity, pretty please?).