I have to say that with my CAH kids, they tend to have what I call "sneaky" fevers.  They start out a tad warm and then can jump suddenly to a raging fever, so I have always been in the practice of tripling at the onset of an illness.  My daughter also tends to vomit when she has a high fever, no matter what the illness, so with her I am especially careful.  My experiences with ear infections have all included raging high fevers with all my kids, CAH or not.  I would think better safe than sorry when it comes to the extra doses in times of illness.