How long have you ran the Kessil 360's on your tank?
Do you think maybe you still need to find that sweet spot?
Many LED users tend to give up rather quickly and blame the lights, although often its the user not finding the sweet-spot. Completely normal feeling for everyone who has indulged in the LED trend. I, myself, was completely frustrated after buying two Hydra 26 HD's (coming from an ATI 6x24 Dimmable) because my Acropora did not look that great. Though after speaking with other Hydra users and trying various profiles, I finally found that sweet spot. My Acroporas never looked so bright!
However, maybe you have attempted various times to find that sweet-spot. Sometimes you just can't, I guess...
Adding T5's always seem to be an awesome solution to improve coral quality.
That being said, would you be interested in making or having-made a floating canopy? Those always look slick over rimless tanks and allow you to hide your lighting inside of them. You could have your three Kessil 360's along with 2 Retrofit T5's in front and back.
OR
You can even look for a used MH/T5 combo fixture. I've seen a few of those reformatted for LED/T5. Makes it look clean by simply removing the metal halides in the fixture and replacing those with the Kessils. This will be nice because the T5's will already be neatly fitted and wired into the fixture.
Here is an example:
This tank and setup belongs to terry4505 on his 120. The thread this is posted in is dedicated to high-end LED's with T5 supplements. Can be found here:
http://www.reefcentral.com/forums/showthread.php?p=24470443