While I think the dimmable lights are really cool, they are not really necessary for a successful tank. I think the icecap ballast is worth the money, but the dimming module costs more than the ballast! I recommend getting the icecap 660, and if you have more cash later on, you could add the dimmer. The 440 cannot be dimmed. I personally think the money would be much better spent on something like a calcium reactor or dosing pump. The corals will live just fine without dimming.
Sonny