The number one thing that t5 systems have an advantage is the control of color. other things would be heat and power usage. Dont get me wrong, I wouldn't mind having a MH at all especially if it was a radium bulb. Take a look around at different pictures and see what color you're going for. I will be adding a supplemental royal blue LED strip to my t5 set up for an even better pop than what i already have. Some of the most colorful reefs that you see on the net have t5 lighting with mh. if you really wanna be happy do both!