I use Reptile Relief as a preventative in my snake room because it is safe to use on and around the snakes. PAM is not safe to use on snakes and it scares the heck out of me. However, I do keep a couple of cans around just in case. I've read a lot about the NIX treatment, but have not used it. I'm not sure why there is such a strong following for PAM as I've read of problems from people using it. It may be great at killing mites, but it can also kill your snakes if you are not very careful. Reptile Relief seems like a much safer product to me. Heck, even the NIX treatment sounds like a safer product to me.
I think in the end, you have to do what you feel is best for your collection. For some people, that is PAM for others it is a different treatment.