If the light is high quality, the corals will thrive under more light. If the light is not high quality, then then can burn and suffer especially with hot spots from diodes.
I grew colonies into canteloupe sizes under the sun one summer in Missouri from 1" frags. The system shared water with my main system (the only way that I could keep it cool) and the frags inside got to like baseball size under MH.
In my whole reefing time, adding more halides, VHO or T5 just meant adding more growth and color (except for the true deepwaters which still grew fast, but lightened up a bit).