I don't have a cat in the fight over crimping but I would like to point out that personal experience is not always required to make an informed decision. I can learn a lot about the moon by talking to the people who went there, I don't have to do it myself.
I can guarantee that if crimping made for better accuracy, in the guns and with the loads that are used in competition, they WOULD be doing it. Those guys don't care about extra steps or a few bucks for another die. They want to win. Somebody in that game tests EVERYTHING that comes around and if it works, they do it. If they do it, others catch on and THEY do it. There's no way that the Lee FCD or any other crimp die makes THEIR ammo and guns more accurate. If it did, they WOULD be using it.
That said, those guns are a long way from our "normal" guns. We don't normally have $1,000 perfectly square actions and recoil lugs, perfectly bedded actions, $500 stocks, guns built by master gun-smiths, $600+ barrels, concentricity gauges, etc, and our entire die sets often cost 1/5th what those guys pay for a seating die.
Does a light crimp with the FCD or any other die help overcome some of the inadequacies in "normal" guns? I think maybe. Used correctly, there's evidence that it might. I say try it and find out.
In a high-end competition gun, no.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.