Like yourself, I too underestimated T5's and my corals got burned, literally.

Concerning softies like zoo's and acans, I cannot put them any where other then the bottom quarter of the tank. The lights are just too intense for them.
I have also been going through a lightening of corals. I have begun to get deeper coloration by doing the following:
* I believe that the T5 setup I have may be too bright for many of the corals. I have noticed increased polyp expansion and the acans are opening up much better.
Most of the day I will run only five bulbs, for 10 hours. I will run the last two bulbs for four hours a day.
This is how it will go:
12:00-10:00PM (Blue+, Blue+)
12:15-9:45PM (Aquablue Special, Aquablue Special, Blue+)
3:00-7:00PM (Aquablue Special, Pro Color)
* I have begun to dose more Reefbooster (AA). This has helped my corals maintain vibrancy and color.
If the photoperiod is not working for you, raising the fixture may be the solution.
Most T5 tanks I have seen tend to have corals with lighter coloration, so it may not be something we can get around.
Finding the cause and solution to coral coloration and appearance can sometimes be tricky.
Anything I missed?