Tack, bitless bridles?

I am very interested in bitless bridles; I am ordering a Dr. Cook's Bitless Bridle very soon. They have a 30 day money back guarantee, so I can send it back if Sementa doesn't go well in it. Over at Equine Ink there is a lot of info regarding diff types of bitless bridles; she found that her horse went well in a Micklem Multibridle.  If the Dr. Cooks doesn't work out, that will be the next one I try. here is a link to that post: http://equineink.com/2008/09/30/dr-cooks-bitless-bridle-will-a-cross-under-design-work-for-your-horse/