Light Question!

I know this has been debated before, but I'm having trouble finding a solid answer... if there is one.

Say my grow space is 4'x4' which in theory could be covered with a 400W HID light which should put out enough lumens for the garden, right? Well what if I were to put a 1000W HID system in? Would I get bigger plants or is this just a waste of light? Is there a restriction on how much light a plant can intake or is it "the more the merrier"? Keep in mind exhausting and any other obstacle is not an issue.

more light never sucks. more heat sucks.

Lynch is correct. The more light, the better! But only as long as you can keep the heat down in your area. I've not had any experience in a long time with anything more than my 400w HPS light, but I can imagine that in a smaller space a 1000w lighting system would end up pretty warm.