I would love to sit in on one of his regular classes in the city, but I have only done seminars with him in Massachusetts. It's always eye-opening to be able to get on the mat with a student of Dojunim Choi, Yong-Sul.
His technique was very powerful. He took techniques that everyone knew and then showed, by using basic principles, how to apply them on a resistant opponent with a strong grab without the use of a fake or a strike. I thought it was great. I have noticed this with other students of Dojunim Choi, that many of his students apply these principles, but few talk about this when instructing. It's a shame because it really is something that sets Hapkido apart from "just a style that studies alot of joint locks."
Hopefully when I get back from Korea and the jetlag goes away I would like to schedule a time to go there and say hi and, if possible, get on the mat.