I bought my medium Burn in 2007. I weigh 190-195. At that time, the advice I received from shops and some reading online was that the medium had ample volume for that weight and a large would be too big. Since it was hard to find large Burns to demo, I demoed a medium, liked it, and bought it. I've been pretty happy with it, but as I pack on a couple more lbs and find myself lower in the water, I've questioned whether I should be in a large. More and more, I keep seeing people in this weight range choose a large.
I guess this is the long way of saying, opinions vary, so demoing is ideal. Oh, and figure how much you'll weigh in five years!