I haven't reviewed LeClairs book in some time, so I may be wrong, but I don't believe LeClair discusses various threads. The book did come with a sample of thread which you must strip, which reinforces my thought that this type of thread is the only type that is discussed.
I strongly recommend practicing with various types of thread, to see which you prefer best. The monofilament threads that are thicker tend to be a little more reflective to light, which may be detrimental. Monofilament has the properties similar to human hair.
Nylon is less reflective IMO, and stretches slightly. I prefer this type and use a modified LeClair hookup.
Direction of light is critical. Movement of the object independent of your body is critical. Absence of 'wobble/bouncing' effect is critical.
Also to all thread workers, please dont abuse and overuse IT work. Its about the effect, not "...and I can't even see the string!..."