Wow this is definately a thread slamming on t5's.
It really depends on what the original poster wants. He/She should see different tanks and judge for themselves. I've seen people switch from MH -> T5 and were happy and I've seen people who switched back to MH because they weren't happy with the T5's.
I personally have the T5's and am very happy with them. I will say that even though many have mentioned that MH and T5's produce the same amount of heat, the hottest my tank gets during the summer in california is about 81 degrees WITHOUT a chiller. You can believe what you want with T5's dispersing heat over a larger area, yaddy yaddy yaddy... but by maintaining a tank WITHOUT a chiller is so much nicer during the summer.
There are lots of opinions about either lights, but I've been very happy with the growth on my tank and do think that my corals color up very nicely even nicer than some MH tanks... Each to their own! Cheers!