You have to take in consideration the longer reach on more recent bikes. With a slack seat tube we would be too fare from the cockpit. You might have a transition period to getting used to the steeper STA. I went from an Intense spider 2013 73.5 STA to a Ripmo V1 76. You can feel the difference on the flat but the climbing position is so much better, and going downhill the long reach is amazing... When I try a bike with slacker STA (like my brother's Hightower and Spec Epic) it feels so weird and inadequate...