I think it depends on how comfortable you feel with your Copic abilities. If you feel like you have a good handle on using them and feel satisfied with your results, then the class might not seem worth it. I have not taken any advanced classes so I have no opinion one way or the other on that.
ETA: no matter what you decide, I'm sure you'll learn something you didn't already know. Personally, I have no art background and really have no desire to color like an artist. I'm an amateur and I'm okay with that. If your desire is to learn to color with professional results, it might be worth checking out. I just know that for my own personal needs and abilities, the standard class was as far as I needed to take it.
Last edited by Novell; 08-05-2011 at 09:39 AM..
Reason: more thoughts