Well, I've tried this info-gathering in 3 different places, and no info, which I find quite strange.
I'll fill you in on my choice and why, which is driven by a bulb-hungry MH/HO combo rig, for an lps tank...good, but huge, and power-hungry AND you have to change out the bulbs. It was a great light kit for my 54, but not enough for my 30x30x30 quarter-cylinder 105 gallon. I was having mystery problems, and began to ask myself if it could really be the lights.
Yes. It was.
So...my next problem: that 30" deep. I began to realize most lights don't do well quite that deep. THat's going to limit my selection: there's one commercial model: Radion Pro, that will handle the depth. THe other choice would be to try to DIY a kit that would work...but DIYing a kit for an already problematic situation was offputting.
I'm quite handy and tech-savvy, but I don't have the time needed to get into the research that it would take to DIY or go from kit---PROBABLY I could do it, but it's an expensive mistake if I can't.
So, I bit the bullet and got the pricier version of the Radions, the Pro, which can do the depth, and my next question is whether they could handle the width. THat's 30".
Quarter-cylinder tank shape means I can do a pyramid rock stack. That brought me within the profile of this unit. Now, here is where Radion's info is a wee bit short....they don't give their profile in inches. They recommend it for 'deep' and also for 'wide.'
I can say it's worked. I didn't get two things, the hanging kit (I have a canopy) and the unit that talks to your computer (it has a usb I leave plugged in, which I can plug into a laptop.) I mounted it directly to the canopy lid with 4 keyhole brackets 'stopped' from movement (because I don't want to have the unit fall off.)
I could only afford one of these.
It lets you arrange your own schedule, eminently modifiable, and there are people posting their settings; but Radion also provides a number of good preset programs. I haven't used the thunderstorms or the directional sun, but I have engaged the moon phase that controls the night lighting. I did use a preset program, one called something like Radiance, that just showcases the color changes, dawn to dark, and it turns out to give the fish their choice about when to be out. Not surprisingly, they kind of take cover during the bright light. I'm running it on 50% output, and the corals are about 8" from the bottom---this is a 'starting out' phase tank.
You also have to be VERY careful not to let your unit get wet, and in my canopy this meant putting a glass between the unit and the water: it has not affected the corals, to my observation.
As far as what you have to do to maintain it---power outage happens, light comes on, and it comes on at the correct phase for the time of day. It remembers. You get a new coral and want to do light-acclimation---it has a setting for that. Tell it how many days you want this to run, and it does the figuring turns itself on and off and reduces the percentage, and then at the end of the period, gets itself back to its regular schedule.
Want to change things---attach the computer, tell it, and detach the computer.
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Now, we have a Marineland LED on the freshwater tank, that does very nicely for freshwater planted and cost half what the Radion did. It however mounts on stilts above the water, and having learned from one unit blown by water, we mounted the next one on a glass bridge we built to protect it. It's a nice dependable unit, but doesn't do phases---it's just on or it's off; and if you have a power failure with this one, you have to find a way to turn it back on at precisely 3pm (set a timer) so that it will get itself back on schedule. If you have a fish-only and don't mind a lower light level (the fish actually like it) this is a good affordable unit. They're both LEDs and very apt for what they do.
Those are the only two reviews I can give by experience, and it's not what you'd call 'enlightened,' pardon pun, but it is what I have found in going from MH and HO to LED with no expertise in the matter. A par meter would be nice, but as long as the corals are happy and the fish are, with the one, I'm good; and as long as the other unit just keeps running and stays dry, we're also happy.
Pay for themselves in bulbs? Well, maybe in five years on the Radion. But we're also drinking a little less electricity than the MH/HO with two ballasts sucked down. I say if it lasts five years with no MH/HO bulb purchases it will have at least paid back some considerable part of the cost. If you're just starting in the hobby, it's a big hit in expense, but if I were starting now, a good LED is the way I would go.
I do urge you to read the contrary opinions of some people dealing with corals. There are two opinions: tanks differ, coral choices differ, and so on, so consider all advice.
