I read on the lighting forum, and also Robthorn used both, and mentioned he had more success with the ATI vs. Geis Powerchrome. Honestly, I have been real happy, but thought I would give a try just to see if there is any difference, in terms of growth and color. I have the blue bulbs you are referring to, and the colors really stand out under the the dusk/ dawn lighting on my tank. I am sure you will be happy with the decisions you have made with your lighting scheme, so will the local power company....LOL..
Perry