David, I have been considering qi for quite some time and I think that the fascia is the key to first experiencing qi. It is the medium
for qi as it is interwoven with every system of the body. I think it is responsible for much of the "stupid jin tricks" many can do. The physical sensation is not a tangible or necessarily measurable thing but rather a connection
or sensation of interaction between the various physical senses and systems (myofascial, endocrine, nervous, emotional, digestive) and your environment. If you don't already practice I would recommend trying the exercises described in the link below.
Qi training includes refining many things and bringing many things you thought of as autonomic to conscious forefront. Not just physical sensations but it is also important to resolve the psychodrama that arises as you practice. Many people say to ignore this in martial arts practice. Yes, ignore the emotion for your martial practice as your intent
during practice should be martial but your goal should be holistic improvement as a person so address the emotional issues afterward or you can do it through martial practice if you so choose.
You can start applying these principles to the rest of your life too. Increased nociception is a benefit I've gained from simplifying my diet. Better pattern recognition, increased background noise recognition, situational awareness, all of these things can be trained to increase your effectiveness as a fighter and as a person.
Here is a very interesting study.
Dietary change greatly enhances your perception of qi as well. Look into bigu practices or shamanic preparatory diets from other cultures. I recommend the Macrobiotic Diet as a good start and then going into a modified bigu or even full bigu if you have a good instructor.
Basically the idea is that you eliminate toxins in your body so your various systems can function better and you can become more conscious of them and what is good and bad for them. Listening to your qi about the cold runs throughout shamanic and martial practices from the cold water dowsings in Systema to the cave and waterfall meditations of the Taoists. If I recall correctly it has something to do with making you shift your nervous system usage.
Feel free to PM me and I have lots of information in my blog as well.