The flex made for a very comfortable ride--cushioned the shock of routine bumps very nicely--but if someone accelerated off the front and I wanted to stay with them, a portion of my initial burst of energy would be absorbed in the flex, creating a lag in my response. That meant I had to work harder to keep from getting dropped (hard enough for me already!) Over the course of a ride, repeatedly paying that penalty meant less energy in reserve if I wanted to break away. That certainly seems to be the rationale for serious competition frames to be beefier and have more rigid geometry.