one might consider that a room chiller haha. but when you have central heat and air, and it's not in the main living area, like a dedicated fish room, the temp in that room can raise substantially, and yet the AC won't kick on because the house temp hasnt raised. just too many disadvantages to MH for me to ever go back, too hot, too much electricity, high replacement cost(tired of hearing about $15 bulbs, they don't compare when you get into high end corals. You could grow leathers with CFL bulb) No tuneability with MH either, you either raise or lower them.same with T5s on these issues. exhaust fans are loud. there are too many nice brands of LEDS out there, that have been proven in huge well known systems to not take the dive. you can make all the excuses in the world, they've been around long enough for the "new and untested" hype to have worn off. they work great, the pros far outweigh any cons when compared to other light sources.
TL;DR
If you won't skimp on other aspects of your reef tank, why would you on inarguably the most important aspect? Buy a good light.
