as a former roadie and high school athlete when we would train for events we would use heavier equipment ( i was a roller speed skater ) only when it came to race days did we switch to our lighter gear and it dramatically improved are speed. also in high school we would do sprints with small parachutes to add resistance . on my road bike i ran heavier rims and tires for training and switched to the light wieght wheelsets only on days i planned to race . i only raced buddies and did time trials so i was never really a "racer" . all being said i believe there are advantages to be gained by training heavy and competeing light. just my opinion