I don't think Clinton ever gets mad.....I need to take lessons from him on that, b/c I do get mad sometimes and I just have to quit.
The reason that Clinton Anderson doesn't get mad: "Frustration begins where knowledge ends." - I believe that was by Clinton himself.
I'm not too familiar with Parelli, but what I have seen is confusing compared to Clinton. Clinton makes it simple to understand and use. I like to use things from Clinton. Like others have said about using info from several trainers, just remember that the way you train your horse may work on several horses but not always. You need to be able to adapt when it doesn't work, which something from another trainer would.
Someone posted earlier that they saw Clinton make the horse go round and round. Maybe while he was explaining something to the crowd, but his training is to only go around a few times or the horse loses focus on you. Yes, I have seen him have his horse Mindy (she is so awesome!) go around him several times during a clinic. This was not to train her but to show her off to the crowd with what his training can do. She was going around him without him cueing her or any halter or lead rope.
As for the issue with rope halters vs nylon halters, rope halters will get a better response from the horse. Some people say that a rope halter will give the horse rope burn across the pole and/or nose. With a nylon halter, the pressure on the horse is disspursed over a greater area, so they really could pull all day without bothering them. If you use a rope halter, the thinner the rope, the more response you will get. Also, tie the halter RIGHT! To tie a rope halter, tie the knot BELOW the loop. If you tie it above and the horse pulls back, you will have a hard time getting the knot undone. If you tie it below, all you have to do is move the loop up and the knot becomes loose.