Couple of interesting interviews with Jeffrey Martin, The Study of Non-Symbolic Consciousness and The End of Self-Referencing on Buddhist Geeks. Martin has tested and interviewed in depth many people who are experiencing persistent non-symbolic states. His dissertation shows that such people are fairly ordinary in many ways, at least psychologically, and they do report high scores on scales of mystical experience. While psychologically normal in many ways, they seem to be happy, and free of anxiety and depression.
A couple of youtube links featuring Jeffrey Martin:
Neurological and Psychological Correlates of Enlightenment
Hacking Your Enlightenment