I run a RK2 on my SPS tank (50gal, 10gal sump), and a RK on my AquaPod. I think they're great for your 75 and under tanks, I woudln't want to put 3 MH and a Chiller one one circuit like they'd require (outside of the expansion) for a larger tank, but it handles my 50 (including a chiller because I live in Texas) just fine. I've never had any issues/errors or problems with it.
On my SPS it runs light, light, heater, chiller, empty, skimmer, skimmer, sump pump (I plug non on/off devices into a seperate power strip aka tunze, auto-top off) I also use the PH monitoring more for kicks as my calcium is by dosing pump.
On the AquaPod it's light, light, heater, empty, ml, empty, pump, powerhead.
PW