I use it on my 50g LPS tank. It's not all it's cracked up to be. I have a ton of the DIY AFR from BRS still to use. Will likely last me years at this rate. I'll sell it locally after this next bottle though.
For example, on my 50g tank I keep alkalinity around 8.5dkh. With AFR my calcium is creeping up past 500 (started at 440) and the ONLY way to remedy that is water changes to bring calcium down. A major flaw with single solution dosing is the inability to dose individual elements that your tank calls for. Very few, if any, tanks actually consume elements in the ratio found in AFR. I've seen a few ICP tests from tanks that have been on AFR for over a year and they aren't the best. Another downside to AFR is my tank has developed a dark green, almost black cyano of some kind. It doesn't really spread so I leave it alone for the most part. Just odd how it popped up about a month after starting AFR. Since AFR has a carbon dosing component to it, it is plausible the AFR has caused the issue.
My 120g uses 70ml of alk and 70ml of calcium right now. AFR couldn't keep up with consumption even if I wanted to use it.