It'd be hard to argue against a Radion, and I'm not going to do so. They have a great reputation, and a great product. I'm sure you'll be happy with it. I looked long and hard before buying a halo, and honestly, I was nervous about it, hoping I made the right choice. Still am, really.
The Halo is less popular, less controllable (and less expensive) but it seemed like a perfect fit for my needs. The small, cube shape just looks 'right' over an open top cube. Light spillage around the tank is minimal (important to me, it's in my living room), coverage within the tank is excellent. 'Disco ball' effect is minimal, I love the mount, with the cable hidden inside. It doesn't have all the fancy software, but I can quickly and easily change intensity and blue/white balance... compared to the halides I'm used to, it's great. Tank runs nice and cool. No noise, much lower electrical usage. The timers are sufficient for my needs... In short, I like it, so far. Unfortunately, I haven't had it long enough to look at growth rates and such.
I can say that I'm starting to get coraline algae growth, and that the few frags I have are doing well. I've got a 2 leptoseris frags low in the tank, a seriatopora, a tri-color Acropora, and a montipora capricornis. All quite small, but the colors pop, polyp extension is good, they look happy.
I'm giving it some break in time right now. Let the system age a bit, dial in my reactors (GAC and GFO) so that the water parameters are stable... I have a few projects I want to get done over the winter, I'm running a water line from my RODI unit through the crawlspace so that I don't have to stretch a hose from the kitchen to refill the ATO container. There's an ugly hanging light fixture over the aquarium that I want to replace with a can light... just minor things, really.
I hope to buy a nice mix of SPS frags and some clams next spring, really get this thing going. My mantra with this tank has been, and will remain... No hurry, take your time, do the research, and get it right the first time. So far so good
