I agree with Chris. I have had a controller for about a year and a half and have yet to feel I need salinity measuring for it. my refractometer does that for me in a snap.
I have a reefkeeper elite. It works very well for me. I started off with teh Reefkeeper Lite. One disadvantage of the LIte is that you can only hook up a max of 4 modules. on my system now, I have 2 powerbars, the system Lab (PH, Temp and Orp plus 2 switches) the Net Module, advanced light controls (for LED Dimming) and the head unit. I like the RSS feeds it send out and I have them integrated into Outlook on my desktop so I can always check the stats. its pretty easy to setup.
I know alot of folks here are very happy with their APEX controllers. I cannot speak to those.