Here's what azsarge thinks:
Black sucks. Older gear was made in Black because it was one of the first colors of that type of nylon to be produced. It is old and outdated!
SO IS OD! It is a solid color and therefore is terrible for camoflauge. Pattern camo is better any day of the week for breaking up an outline. Tan is better, since it's a bit more neutral, but still can be deteced quite easy if worn in a darker environment, or one with alot of green.
Subdued, neutral colors are the way to go. Smoke Green/Ranger Green and Coyote Brown are the latest solid camo colors, and provide it better than darker colors like OD and black. After all, look at the new ARMPAT for the Advanced Combat Uniform! Mostly grey!
Think about how long OD has been around. A long time! The reason gear is still made in OD is mostly because of tradition. All issue gear up until recently has been OD, so gear companies produce their designs in the same color to match.
If you want ONE color to wear in all environments, do what the USMC did, and go with a light brown like Coyote Brown. Not Tan, and not a light khaki, BROWN.
Of course, if you want to be 1337, you'd get MultiCam. Outerwear, LBE, pack, everything MultiCam! Then again, that would require you to spend hundreds of dollars.