--but some people never go there, and a lot of "chatting" takes place right in threads . . .

Anyway, to address some of what you wrote--

An abnormal NCV/EMG study does imply at least some dysfunction of the larger, myelinated nerves, as the current technology can really only electrically measure such nerves. AND--it also implies that the damage is severe enough to be noticed, as there can be spotty/patchy damage to such nerves that produces symptoms, but does not show up on such testing.

All motor neurons are myelinated, and thus designated large-fiber, as are the sensory nerves that subsume the sensations of mechanical touch, vibration, and position sense. The smaller, thinly myelinated or un-myelinated nerves are all sensory, and subsume the sensations of pain and temperature. Autonmoic system nerves are also small-fiber.

Typically, people with predominant small-fiber dysfunction have that nasty burning/shooting/lancating/stabbing nerve pain, although depending on what nerves are involved, they may have numbness as well. Sometimes they have both in the same area (and that's really hard to describe to people, even doctors).

But, one can have a mixed type of neuropathy and therefore a wide range of symptoms (many causes damage a wide range of nerve types).

It is true that people with primarily sensory syndromes, especially small-fiber ones, are more likely to be diagnosed as "idiopathic", because medicine currently just does not have all the tools to definitively identify causes of snesory nerve dysfunction--for some reason it's easier to identify things that have motor effects. Various toxins and autoimmune processes are often suspected in "idiopathic" sensory syndromes, as is impaired glucose tolerance prior to diabetes, and a number of hereditary syndromes, but it's very hard to measure such things--and many doctors don't go far enough in testing (such as ordering multi-hour glucose tolerance tests, or a full range of celiac/gluten investigations, or proper genetic screens).