I have been using it over a year. I would not say I have a huge skimmer, but it is over-sized for my tank. My tank is 6 years old. I run a DSB in my main tank, but it was not keeping up....... It has worked well for me, but you do need to be careful. I have about 120gal of water in my system, and I'm at about 1ml per day for maintenance dose. The other reason that I use it is because it is cheap......no need for GFO, no need to grow algea in the sump.
1) Start low, where everyone says to, but do not boost your levels too high. Just stay lower and let it work.
2) If you drive everything to unmeasurable, you'll get very low nutrients, and it will tend to lighten the color of the corals. I tried dosing aminos to keep the color, but I now just backed off my dose, and use it to maintain my NO3 right at the barely detectable range.