This post assumes a belief in spirituality so I'm not interested in debating that specifically. If you want to please start your own thread.
From what I can see, reiki is channeling occult energy through people's bodies and is therefore potentially risky. It seems to me that new age practitioners will repeatedly say they don't believe in malevolent entities but I think this is naive.
One of my friends told me that his dad was never the same after he became involved with reiki.
And also nearly everyone I've met who has done it was told by the reiki practitioner that they are 'special' have a 'gift' or could easily become a reiki master.