A hood makes a big difference.
I have a big parabolic (sp) hood for growth. The 1000w light hangs vertical. The light the hood puts off is nice and even. Not as bright as a horizontal light but at this stage Im looking for big even coverage and its not as intense as my flowering room. As I stated before a horizontal light is more intense. So I have 4 1000w lights in cool tubes laying horizontal for my flower room. People that ditch the hood are losing lots of valuable lumens that the plant could be using instead of the ceiling.