I tried but was not happy with the ability to get a perfect measurement achieved. The tying and re-tying became a boorish task. And at the time I was changing tailpieces often, which meant a lot of time spent messing with the cord. Unscrewing a tail cord is just so much easier. Having said that, if I ever finalize a violin setup, I will probably use the kevlar cord.
Some of what is sold as kevlar is not actually kevlar. There is another name (which escapes me right now,,,I'll probably jerk out of sleep at 2am screaming the name)but from what I remember this other material is more slippery and does not hold a knot well.

Can't remember.  It's been a couple of years since I've messed with it and it's hard for me now to remember names.  I call the old lady that walks around in this house "hon" just so I won't stumble and call out the wrong name,,,,and she's been here since '72.