I use the T5s (so far) for four hours a day at 100%. I've been using the T5s mostly for the blues and the T5s to provide more of the white-ish light. During the ramp up and down on the LEDs they have more blue in them. I absolutely LOVE the light though. Best light I've ever owned that wasn't halide and T5.
Have a 8 bulb 36 inch fixture. Love it. Only downside is changing bulbs. I used a par meter to get the par I wanted but it was with used bulbs. Am starting to change a bulb a week this week. Those LEDs are powerful. I fried a green slimmer with them set to high.
Good fixture for sure. All you have to do is pick one up to tell they are built for duty. Heavy!!
Jim