How often are you actually attempting the techniques your instructor is teaching you? Your instructor sort of has to evaluate you based on strengths and weaknesses and application of what he teaches you. I also have to say, every story like this I ever heard (but I tap so and so and so and so cant tap me) looked a whole lot different in the gym, and the complaintant was usually very, very deficient in some area that was very important (side control escape, moving the hips when in a bad position, etc). If this isnt the case, stick with it, but if you are not attempting the things you drill and are taught with these guys while you are there, why bother?