Is it a clinic with Linda and Pat, or a clinic with one of their Parelli instructors? I personally like the methods that they use for certain horses, especially when they get into the right-brain/left-brain introvert/extrovert theory. A lot of people may bash this, but the way they can cater their method to a variety of horse personalities (horsenalities) is very handy. I have owned three right-brained (high fear) horses, with one being an introvert (Minnie, though occasionally extroverted) and one being an extrovert (Flicka, Flame). Methods that include a lot of pressure and pushing, i.e. Clinton Anderson and the like, just cause them to explode and you get no where.
I have not personally attended one of their clinics, but my start in horses was underneath a group of older women that followed the method and used it on their horses. One of them was very well versed in the Parelli method, and was far into the liberty work that they do (level 4) and the way she could communicate with her horse was amazing. All of their horses were a pleasure to be around, and they helped me get my previously abused mare (Flame) over a lot of her baggage.
Some Parelli followers don't use the method properly, and their horses are rude, but when you take the right stuff and apply it the right way, it works. I would go and audit, and if you are interested, Parelli has a bunch of online courses and what not.
Toofine - 1998 Half Arabian
Minnie - 2013 Morgan