I have to say the coralife metal halide are very well made and better than AquaMedic (I never have an AquaMedic light that did not give me some sort of trouble regardless bought new or used.) But I never have problem with Coralife.
Also, you won't get help if your AquaMedic product is in trouble but Coralife responded very fast (once I suspected a PC bulb is damage in transit).