Why? Maybe a few good ones, depending on where you use the saw (Federal lands, for example). While the idea of letting the pent-up heat out of the muffler makes sense to me in terms of increasing longevity, I have some reservation about the bottom-ends lasting less long when more than just opening the muffler is done. I've got some mechanical engineering blood in me, which is why I harbor that reservation.
At any rate, Mark, that feature has been available on the 036 for several years and in the 2000 catalog I'm viewing just now, they're showing 1995 as the introductory year for the "Dual Braking System".
Glen