Elway did get to the Super Bowl 3 times before Davis was in the backfield, and made the playoffs 10 times. In any case, Elway was something of a gunslinger by nature, whereas Aikman was more of a QB who wanted to run the system like well oiled machine.
I think it's a bit misleading when people refer to Aikman a bus driver though, because he was more integral to the well oil machine than just a guy who was manning the position and trying not to screw it up, which is the image I think people have with the label "bus driver". He kept the troops line, demanded precision and hard work, and was in complete control of the offense. He was the man in charge.
Elway's numbers in those Terrell Davis/Super Bowl winning years were really very similar to most of his career. He had a few years scattered through his career where he had bigger yardage totals and ypg averages, but for the most part the totals and averages were well in line with his career. He was more efficient though with Davis - slightly more TDs and a better TD/INT ratio.