Hello,
I’m currently using both in my sps system.
Visually, indeed the XR15 seems to illuminate much more than the Kessil. Again, visually!
No doubt that the light from Kessil is way more charming (shimmer). Once again, visually!
Said that, for the tank size that you mentioned, any choice you will be well served.
I have same sps frags under Radion and Kessil... and between both... it is a bit early, but so far not much big differences.
At least this is a nice doubt.
Today, I’m not sure which one to pick if I need to select only one.
Maybe Radion because I also have MP40, Vectra... so everything via Mobius...