I'm another TEK user. I'm more than happy with my light, but would have gone ATI fi I could justify the extra money. I see the ATI really showing its superiority over deeper tanks. I have my TEK 6 bulb mounted 16" above my 40br and it's still plenty for my SPS and clam. I think I'd have to mount the ATI directly to the ceiling from everything I've read, haha! I don't think you could lose either way.