I currently train with Professor Buckwitz at CSNYCBJJ and I have to say that after training with several teachers over the last 10 years that his knowledge of practical and efficient BJJ is truly excellent. It can also be difficult to find knowledgeable people who can also teach but his creativity and patience make for a very enjoyable learning experience.
Each session the learnt skill level is high as well as the cardio level. I leave there a sweaty mess each class. Buck values technique over strength and timing over twitchy so there is low chance of serious injury.
This guy knows his stuff. Period.