Well.. let me put it this way.
if i dont have sps and if i keep lps and Nems ..i wouldnt do any other led than kessil .. but now with Josh igniting my sps bug back again with his generous frags ( more like mini colonies ) and them thriving in my tank ..i wanted to keep em all lol sps, lps everything ..
i have reviewed and compared almost all leds, mh and t5 ..
out of leds only kessils and radions stood out ..
Kessils because : i am as you see mostly chalice guy and love chalices of all the corals .. Nothing ever colors them up better than kessil, i was asked if i am keeping them under MH when i had them under kessil .. and so is the case with acans .. Rainbow acans wont turn orange under kessil ..
Radions cause : they are extremely powerful .. didnt realize how much power they had until i had the fixture mounted on the tank .. their TIR is makes the difference between other fixtures with same wattage and radions .. oh another thing i liked the most in radion is their interface .. again it might seem like a trivial thing but its soo much nicer .. like i can choose the spectrum to be 20k and it would assign all blues at 100% whites at 17% and reds and greens at 17% and instead of indivually setting them to 50% ( if i want the lights at 50% ) i can just slide the brightness to 50% and they are all automatically set to 50% power with out change in the 20k look but less brighter.. love the interface..
MH .. i almost went Giesemann Spectra Fixture .. but didnt because : MH is heat added to the tank and i cant have chalices directly under that light without proper acclimation and i dont have time for it ..
T5 : i just dont like the looks ..none of us who like the look of tank under kessil would like T5 for sure ( 99% )
so summary ..
if i am doing a mixed reef ( with more than some sps ) i would do radion ..
if i am doing chalices, lps or anemones only tank i wouldnt do any other light than a kessil ..
kessil in my experience colors up things beautifully .. but growth is limited ( or takes a while to actually start )
hope this helps