Still running MH's since 2002. BUT I wouldn't miss them if I could change them out! I replaced the tank and restarted my reef in 2019 and I was very ready to switch to LED but did not because I wasn't sure about the durability of LED's in the enclosed space (in the floor joist just inches above the surface of the water) of my reef with high heat and humidity. Plus I knew that 2 400W MH's were proven in my system and grew Acropora very well. I cannot change out light fixtures without totally breaking down and removing the tank. So I stuck with what I knew would work and last. I do have LED envy thinking about how much money and electricity I could be saving (I have to run a chiller as well because of the high heat generated).