First off, there are several types of evergrow LEDs. My comment was for D120 only - I have that one. Other Evergrow LEDs have better colours.
D120 is what made evergrow lights popular. They are incredibly reliable - thousands upon thousands have been sold and used and I haven't heard of too many complaints. In some ways, this is the model T of LED lights. They made LED reef lights accessible to everyone, made cheaply and reliably.
The design has been copied by other chinese LED makers successfully. They are very bright at 100% for both channels. They will cover 24"x16" well I'd say. If your tank is more than 24" I'd get 2. there are par measures on other forums. Flourescent colours in corals are induced by the blue spectrum as my understanding is.
For best flourescent colours you do want a greater range of blue LEDs - that cover from 400 to 470nm. Near 400nm they are often called "UV" but it isn't true UV and it won't cause you any harm at 400nm. Another one is called "Royal Blue" which is in the 450nm area. Then there is the plain "Blue" which is in the 470nm area. The plain "blue" led chips are the cheapest, and D120 has a lot of those in there, and only 7 royal blue, and 4 UV. So it gives very good flourescent colour, but not the best colour. So you have to look at what each LED fixture has in terms of types of LEDs.
If you look at Evergrow's programmable fixtures, like IT2040, etc. those have considerably more of the "royal blue" in them then the plain "blue". Those I believe would put out better colour rendition. For a bit more money you can better colours AND programmability to boot.
That said, I did see a LOT of folks at the Fragfest using the D120 and their clones to light their displays, including Reef Hero and their corals including SPS looked AWESOME. So the D120 will surprise you with what it can do.
And final plug for Evergrow. From what I can see evergrow is a ton more reliable than some of the more expensive upmarket brands which have had incidents of parts or boards burning on them just outside the warranty period.
ReefSupplies has all the variants of Evergrow as do a few local stores. There are reliable D120 clones on ebay that are cheaper and just as well made. Mars is a brand that comes to my mind immediately. I hope that helps?