I have been to a bunch of clinics, no masterclasses, and the thing I like the most is the time the drummers spend talking about their experiences and not so much chops. At the beginning of most they will play to a song or two just to wake every one up, but beyond that, it's very difficult to pick up a lot of technique in a setting like that.
Most have talked about their set up, they are there also to sell, and mention their sponsors. All of them have been very good at answering questions and hanging out afterward to sign autographs. You will find though that a few have done enough clinics that they will tell you what they will do rather than ask you for an agenda. All have been fun and informative. Also I have been to most that are free and a few that charge for entry.