Have you looked at apex or reef angel? I ask because if you go and read through the DA support forums, you'll find a number of really frustrated people asking when the next software update is coming (it's been well over a year), and when they're going to fix the SL2 (they had a debocle with the saltwater probe that they still haven't addressed)... DA has really dropped the ball recently, there's a lot of unhappy customers. I'm not bashing them for the sake of bashing them, but it is the unfortunate truth to the situation.
Overall i'm mostly happy with my RKE. I have a bus wire going ~25 feet from my display back to my fish closet, and i get a pile of bus errors about once a week. Most of the time it's stable, but sometimes when the MH lights turn on the alarms go off... I put choke's on my MH ballasts (which is the usual solution for this according to their forums), and separated everything i can as far as i can, but it's still occasionally giving me problems. They claim this is supported, but the bus cables are unshielded as best i can tell, they're just 6 wire phone wires (wired specially, don't use off the shelf cables), and their bus system seems very susceptible to interference.
just my .02