Dont worry. Thats not to much light. Thats probaly more realisticly in the middle of the light range for a reef.
Taking bulbs out may or may not cause others to light. Some ballasts require all 4 bulbs before they will work properly.
I have 440W of VHO
over a 75 gal
tank and everything is fine. If you wanted you could even do a dual MH
setup with two VHO
bulbs. That would give you at least 570W of light or 720W depending if you did 175W MH
or 250W MH
Now if you had say a pair of 1000W MH
bulbs over the tank then you might be a bit excessive. As you can see you really have to go crazy with lights before you have to much.