They must have done the tapers for a good reason. Couldn't have been easy to produce those tubes.

As far as the "fast" thing, my guess is a perfect storm of 12 other variables are matching up better with the given cdale frame stiffness here than other bikes with less or more stiffness. And it does match for the way some folks ride and what setup they like to run. And for some folks not so much. Anyway enough of an effect for a second or two on a ride from what we're reading here.