David, I wrote the article in the Guitarfish link you referenced. The Radion gives a ton of features and PAR. I get some of the reddest purples/reds in the tank with the Radion than any of the other tanks I keep.
That said, there are some notable drawbacks:
1. Spotlight: Since the Radion is a puck-based LED fixture, the areas directly under the light are very well lit, but the intensity drops off significantly as you move outward from the center. Unless all your scapes are center mounds, I'd recommend 1 fixture for every 24" of width of tank.
2. Color: To help compensate for the above, I find myself wanting to maximize PAR output. In order to achieve this, I have to add more blue light than I really want to. This results in much less pleasing color casting.
3. Fan / hanging: Not necessarily a drawback, but you do need to mount this light overhead, and note that it does have a fan. It's not super loud, but it does collect dust and any mechanical parts like this will wear out over time.
4. Computer control: While the flexibility is nice, without the extra accessory, you have a physically connect a laptop via USB. For things like daylight savings changes, it's far easier to do that twice a year on my other fixtures, than to fire up the laptop, connect, reinstall the radion software, etc...
For me, for the same money (or less), I've leaned toward BuildMyLED fixtures with a controller. It address the issues I list above, produces tons of light, and still has a decent amount of functionality with the controller. Of course, much of the above is circumstance and preference, so YMMV.