I don't remember who posted it or the title, but someone put up the speeds comparing the years a few months ago. And if I remember right there wasn't but about 1-2 fps difference between the "horn" bows he tested ('64, '65, '66). I don't remember how the '62 and older bows did, but they were very near the same.
It kind of surprized me, after all I'd read I expected the '64 to be 10 fps or more faster.