One factor to consider is wether or not you will have any additional ambient lighting in the room like chandeliers or wall sconces. Obviously the brighter the fixture is the farther up it will travel and also the better saturation of color you will have. I personally have used fixtures with 10mm LED's, 1 watt LED's, and 3 watt LED's. I would recommend using the 1 watt LED version to give you even coverage all the way. The only challenge to watch out for is if you have a fixture that has separate red, green, and blue LED's when you put the light under an object on the wall, like a wall sconce, you will end up with a different color shadow becaus ethe light will block some of the color. I now only use fixtures with Tri color LED's to avoid the issue, it's not perfect but it is close enough to it.
