How much is too much light

My friend has had a 400w hps on a 2.25 square foot area for most of his grow. He found another 150 and is debating putting over them too making it a total of 550 in a 2.25 ft2 area of plant matter. A fan is keeping the canopy at 75 degrees with them 9 inches away. Is there anything he should worry about besides heat with that much light per foot2. It came out to about 200w per foot2 and 25000 lumens.

As long as it doesn't get too hot and burn the leaves you will be fine.

as long as ur eyes dont catch on fire and burst and pop out ur head,.ull be fine