I've run the AC 14k DE, Megachrome Marine, and Megachrome Corals (received mine yesterday) and color/intensitywise, the Corals bulb is my favorite.
The color is not very different compared to the Marine bulb, but it makes the water and corals look obviously more crisp. When I put my hand directly under the bulb, outside of the water, you can easily see that the Marine bulb looks more yellow, and the Corals bulb more blue.
I'm greatly relieved that Giesemann didn't put out a bulb that makes your water look really blue. There are so many of these bulbs out on the market already.
Of the 3, the AC 14k is my least favorite.
I should mention that I ran all 3 bulbs on a Giesemann electronic ballast, so your results will vary.