Big fan boi of Cribby's!

Done 3 of his courses and my sailing has improved significantly.
What you can learn is only limited by the time and energy that you have available.
I have improved my gybes, tacks, wavesailing and most importantly these skills have enabled me to get stoked sailing pretty crappy conditions because I can get so much more out of them.
Do it!
Cribby is very good at constructive critique. To get the most out of the course you must be prepared to just get in to the whole approach (check your ego at the door) and not try and justify what you currently do. His methods have been honed over thousands of people. Sometimes it is hard to see / hear your efforts being broken down but the results are worth it.