"Think about it if you have a problem steering you should probably start with your rudders."

Count me FIRMLY in the sails and mast trim first camp! Whenever I have a problem steering it is always because I have too much tension on the main sheet or too little jib tension, too late.. But I have to admit I'm no expert on cats yet having gained most of my experience on mono's. By all means, check your rudders for normal trim, but I wouldn't be taking a file to them unless it was a last resort. Raking forward does not improve anything IMHO. It just masks a trim problem by adding more force in the opposite direction (AKA drag). Its a bit like "shooting the messenger", if you ask me. Ie: The rudder tells you something is wrong so you take a sharp tool to it and "make him an offer he can't refuse"!
Rick and Marys book has some excellent explanations of the theory behind it all on page 72 and 73.
Dennis