RKL is nice, with the release of myreef 2.0 it was SO SO EASY to program. Like I could have my mom do it!
I have the RKL L3 I think it is RKL, 2 x PC4, temp, pH, SL1.
The cool thing is I found out you can get a hub to plug in to the system and then keep the SID (programmer/reader) plugged in 24/7 then run a longer USB (30 feet in my case) to the computer and save your back!
Bob I would buy it again though the pros definitely out weight the cons.
Only con I have right now is the temp probe I can't seem to calibrate, but that is more likely user error than anything.