I only used it over a few month's time, but my tank did not respond well to it, or perhaps I was dosing incorrectly. Each time some coral would go up in smoke, I immediately backed off dosing for a few weeks.
I don't know if my tank was a poor test subject or if I was just doing it wrong, but last year at MACNA, the person working the Prodibio booth asked me if I would be willing to try it again, and I answered that I probably would, but that is as far as I got.
Several people here have or are using it. You might ask Steve Allen (slallen), as he comes to mind.