I tried today, with trainer difficulty 0, then 100%.
I was left for dead each time.
At 9:45 and 23:30
First time I pushed 9+w/kg at the climb, got dropped like a stone by people doing half that.
Second time I came through the pack to hit the ramp at 46km/h, much faster than most and got dropped again.
(I do know that taking some speed in and hitting it hard at the top it optimal, this was an experiment remember).