I think I'm going to go with the RKL myself as soon as my tax return comes in. I'll be putting it on our 20 gal with a Eshopps, MP10, AC-70 Fuge, and Coralife PC lighting fixture (with lunar lights).
I was a bit bummed that DA won't work with me on a price for the "plus" package, as I wanted to swap the SL1, for the SL2. I understand the SL2 is a bit more expensive, so I'll just have to deal with it. The only other thing that seems to be a bit of an issue, is with each firmware update, you have to do each module individually. That to me is kind of a pain. Luckly I'm a bit of a computer nerd, and won't mind bringing my netbook to the tank to upgrade each module. But for some people, this isn't a very user friendly way of doing things.
Also, someone in a previous post mentioned DA's programing being a bit difficult. I just checked out their site, which has been updated recently, and they are claiming "our easiest programming yet..." Not sure if this is part of a firmware upgrade or not. May be something worth looking into.
-RYknow