I like some of CA methods but not all (I think his idea on how to give shots, for example, is very wrong and I can bet on anything wouldn't work with one of my horses) . I too bought "Ground" series and it does give good ideas on HOW to train basic things like yielding hindquarters and so on, so I think it was a good deal. However I can't be even close as aggressive as he is at some time even with my bossy unrespectfull qh. And using stick (even showing it) on my paint makes her nothing but running very mad and NOT obeying.
I personally don't like Parelli, because found it to be very boring. I thought may be it's just videos, but I went to Parelli clinic at the PA Expo this passed weekend (although it was not Parelli, but one of Parelli-certified instructors), and it was even worse than videos. :(