Mark is a challenging teacher. I really appreciated his consistent focus on form and gentle adjustments to alignment. He offers an incredible workout. I agree with someone else's comment that his beginner classes are not really for beginners. His classes are always packed so you have to be comfortable having your mat 6 inches from your neighbor.
Rebecca is fun - she plays rock and roll music! - and a very open person. She (safely) encourages students to push up against their own boundaries. She likes inversions a bit more than I do but thanks to her, I'm more adventurous on that front now!
I credit Edge Yoga with taking my practice to the next level. I highly recommend this studio despite its small size and the lack of parking. As some others have noted, you hardly notice the bartending school next door once yoga class starts. In addition to the great instruction, I appreciate the way Mark runs his business - he is very customer focused.