Wagtail
Horse servant
I agree that the pessoa is a useful training aid - it was recommended by one of the top equine back vets for a friends warm blood that was recovering from back injury. It has proved extremely useful and helped very much in its rehabilitation. However, like any gadget, it was used in the proper way by a professional person.
Having had some experience with racehorses - they are taught to race in a flat outline with their heads stuck out, so most have physically developed to that way of going. To put draw reins on an exracehorse that throws its head around during transitions would be counter productive in the long run and I would say it is probably finding the transitions too difficult because it is not physically capable, IMO. I would think that more time would be needed to encourage it to work long and low (with a pessoa) to develop topline so there would be no use for draw reins.
Thank you, Hollywood. That is what I was trying to explain to Cptrayes about why using draw reins on such horses is counter productive. But I have obviously not explained it very well.