Excellent test moose!
I just thought that I would bump this, as some of these types of questions have been coming up the last little while.
Interestingly enough, I did a review on the BK9 recently, and it chopped my 4-6in log I was using in almost exactly the same amount of strokes as moose did (26 for mine). Same with the BK2. Mine did it in 45. I just thought it was cool how consistent the blades were. You can expect a 9 to be about twice the chopper of a 2.