Yep, use it quite a bit for layering harmonies/single note lines under choruses. That and the Digitech Freqout layered together often times.
I've got the Joyo one, works great!
Once you learn the sweet spots over the pickups you can kinda aim it where you need it to be while playing to start doing it's thing quickly. It's worth spending some time just fretting one note and pulling it back and forth across the pickups to find the spots it works best in. You can manipulate it to give you the fundamental note and pushing it into the hotter zones it can get up in the higher octave. There's a little unpredictability with them that I particularly dig.
They definitely do the trick in place of a Sustainer pickup!
