One thing I think is obvious, that when people learn the Ari for the sake of the מדרגות or רוח הקודש [miracles or Divine spirit ] that definitely leads them down the path to the dark side. And then even when it seems they have powers, it is always powers from the dark side.
My own experience with this was doing Gemara for a few years in NY and then during the last year there getting involved with the writings of the Ari and then coming to Israel and getting a blast of the Divine light, and then at some point feeling I was getting ריבוי אור sunburn I was trying to turn off the bulb. That would have been the end of the story, except after that I got the impression that turning off the bulb was not the right thing to do, and also the daughter of Bava Sali indicated to me as much. So to make up for the mistake involved in that, I try to make up for it to some degree by blogging and I hope that somewhere maybe from my words someone will be inspired to pick up a Gemara or a book of Musar or Rav Shach's Avi Ezri and by that perhaps I too will eventually merit to learn Torah.
[This idea come from a few books of Musar. I saw the idea of זיכוי הרבים bringing merit to others in אגרת המוסר, חובות לבבות, ומדרגת האדם at least three sources.]
[Added note. The only book of the Ari I did in NY before I got to Israel was the Eitz Chaim.]]