not anecdotal as much as it is based on the seat angle of the frame and femur length of the rider.

and there are a few professional riders that have ridden with zero-setback posts. e.g. Tejay VG. He has a zero setback when he was riding specialized frames when he was on HTC:



and now he is on setback posts now that he's on BMC:



on a personal (anecdotal) note, I recently got a custom frame built up, and designed the geometry so that I could specifically use a zero-setback post