I keep lots of SPS, montis, millies, stylos, acros, etc, nothing too difficult though under all PC lighting. I also haven't changed my bulbs in gasp.... about 2 years. I only drip kalk for supplements. Everything grows great. The only thing that makes my system special possibly is that I have 644W of PC over a 72G. I do keep most of the SPS up near the top for what it is worth. T5's can definatley handle some SPS near the top. I'm actually considering seriously switching over to T5's also.
good luck