A few notes/opinions on florescence and UV LEDs:
1) The source wavelength has little impact on the output.
Other than it must higher energy of course.
https://en.wikipedia.org/wiki/Kasha%27s_rule
So really, RB versus UV is little different as far as fluorescence.
2) The Royal Blue gets though water, acrylic, and glass better than UV.
In some cases, such as tempered glass, WAY better.
That means your UV is getting very attenuated by the time it hits the coral.
3) The UV LEDs are generally less efficient and cost more.
Manufacturing thing. But it means as far as far as cost/florescence,
the UV is a loser.
So : Is UV a bad idea?? Well, there is one key thing:
4) We cannot see UV very well.
If we add a ton of extra RB to make colors "pop", it makes the tank
really start to look blue. Some may like that, some may not.
On the other hand, a lot of UV will make colors "pop" the same, but really
have almost no effect on the look.
Then there is the separate discussion on UV and PAR.