Works well and really keeps the head from detuning. I used to adjust the tuning after 10 practice sessions or so, but I haven't had to do that since I got these screws for a couple of months now,
The only downside is that if you like to finger-tighten the bolts, up to a certain degree in order to have a uniform and even starting point, this is no longer possible. But honestly, this is a small price to pay.
It remains to be seen if they lose their effectiveness over time.