You could but you wouldn't get even light coverage across the tank. You would need to use a par meter to find out where to place your corals also. Depending on how bright your leds were you would probably also have to turn them down to match the T5's. Also if you wanted to use different color t5's like coral plus or blue plus then unless you could get your leds to match the color it wouldnt look very good in the tank. I personally wouldn't do it.
I'm currently waiting on the aquatic life 60" t5 hybrid to pair with my radions. They are suppose to be releasing it next month.