Hi, and thanks for all keep rolling the thread. It's already more and better than I could have hoped for.
I have never tried visionary or other type of shamanic practice. I think the tummo was so compelling for me because I like to be in control of things.
My current approach to tummo stems from several determining experience or occasionally from an insight, here are few examples:
- My very first yoga book included a short description of the tummo practice from the (now I know) naro kacho vajrayogini tradition. As a child I was fascinated by it, although I didn't understand how to halve the A (tibetan characters not included) or how to perform properly the 'pot form breathing' (vase breathing)

.
- There was a yogi. He was also a neuropathologist physician. So, this doctor wrote two or three rather scientific books about the relationship between yoga systems and physiology/ neurophysiology. After reading them I could understand some neuroendocrine-physiologycal principles behind the more mystical/esoteric exercises.
- Loco Austriaco's answers and instructions. I tought I could use it in the investigation of reality as a diving-suit-armor, a perfect and versatile tool.
- I have listened the encouraging Buddhist Geeks interview-episode with Hokai Sobol titled: Vajrayana in Plain English. 'Ah' for non-arising..., the dimensions of the mantras... I could glimpse into the enormus complexity of the most basic vajrayana practices. After some time I speculated on the ngöndro where one began to build up the fractal(?) structure of an interface.
I like the adventure.
Best,
Antoine