Dregan you aren't making a lot of sense. Your "flawless system" is common sense. Dur, I hit a button every 5 seconds to hold aggro. Yeah it works the vast majority of the time. I have no idea how you can possibly regain aggro easily because you don't do anything differently than I do. I'm level 30 and a 33 guardian was having the same problem. Somebody would get aggro because something stupid happens (not tanks fault at all) and then he simply could not get the mob off.
You are the one being hard headed here...