Ok I bought one, tried the Jebao DP-4 doser and it just didn't prove trustworthy after a couple weeks of testing. Cant tell you how many times
I calibrated it and every day it dosed up to 200% of what I had it set to dose. No way I was trusting it with my SPS tank. The GHL wasn't cheap but they were running a 25% off sale and GHL had some great reviews so I bought it.
This unit feels solid and the android app makes it real easy to calibrate and program. Looks like it does a lot more than just dose but I'll explore more once I'm satisfied in its dosing accuracy. My only complaint so far is that it's not iOs compatible so I had to buy a $50 Android tablet to program it (not so bad after the sale price).