I don't think we know enough about what constitutes benefits for corals like you might be meaning.
And I guess 20k vs ??
10K came first, so 20k arguably offered the benefit of a somewhat more realistic "blue-heavy" light environment for the corals. There is that.
Also, I think Sanjay Joshi did some comparative studies on corals grown under 10K and 20K (others?) and 20K pretty much universally colored corals better...or allowed them to color better....whatever. That's the part we don't really know....is more color better? Or less? When is my coral "happy"? LOL.