I do not have first-hand experience with this system, and this is for good reason!! A product like this is cruel and unnecessary. Teaching your horse "naturally" to collect, balance and move correctly is essential; however forcing him to move in an artificial frame with harsh devices such as this is no good.
First of all, I do not even agree with using draw reins when working a horse to "set its head". Even the horses in some of the sales pictures of this system appear overbent and below the bit. This would be the same as teaching a horse to "collect" by forcing it down with heavy hands.
Furthermore, I do not like the idea of the "aids" against the back legs one bit either. I understand their purpose, but do you really think your horse should rely on physical pressure on its hind legs to drive it into collection? You are not going to be able to apply pressure on its hind legs to mimic that while riding. Besides, this device is oppressive and does not allow the horse to develop its muscle gradually and find its own best frame for balance and collection.
My advice to you would be - don't do it. Work your horse so that he learns "naturally", and by naturally I mean with time, muscle-building work, and if you are riding, the cues of your seat and legs, to collect. If you do not have the expertise to teach collection yourself, then you need to seek out a trainer who can help your horse, or who can help you learn more about it.
Please be gentle with your horse and do not resort to oppressive means such as this just because it may seem a "quick fix". In the horse world, a quick fix is never good or long-lasting!