I do enjoy using Parelli..
I tend to mix various styles and come out with a combination where I get the best natural effects. I do like Parelli, but in my opinion, a person may have to search out other avenues to complete some tasks as not all horses and people respond or mesh well with just one training method.
As for the halter.. The links that i clicked on, and viewed, seem pretty much the same as a common flat halter with minor changes. Again, only my thought, but for $44.. If it works for you. I am a tried and true sort, and a general rope halter is where I get the absolute best results. It still amazes me that such a simple design can be so effective and surpass so many mechanical and "new design" types!
Dixon's Red Hot Ember