They would have to be able to prove to me that the 90w LED blub is really equivelent to the 400w HPS. Because I just dont believe it, I am a Master Electrican by trade and I just dont see it giving off the same lumins and light spectrum as that 400w HPS. I would go with what you defineatly knows works and that 150w HPS may be small but, it has worked for many of us.