It really depends on how close you have them to the water. They definitely radiate heat, I can feel it, and it has to be managed. My argument is that it is easy. If I ran my fixture 3-4 inches above the water line and kept my apt at 80, I would need to increase my active cooling. There's a couple things I do which mitigate it though. First I'm running the fixture about 13" above the tank rim. I'm also keeping my apartment mid seventies for temp. Something else I do is I stagger the halides being on. First one on, then both on, then first one off, then second one off.
I don't think it's a function of just climate, but a combination of climate, ambient living space temp you prefer, and cost of electricity combined. For instance, any potential extra cost of running halides would be offset if you lived in a cooler climate and preferred it cooler inside your home. You could run your halides closer to the water, which means you are also saving on heater electricity.
It gets > 100F between March - Oct here, and my AC cranks when I'm home. I run the majority of my halide photoperiod while I'm home, and cooling the apartment anyway. I let it warm up in the apt while I'm at work, and even then, the aquarium heater runs intermittently.
LEDs can produce great results, and if you like yours and are getting the results you want, I wouldn't switch. For me, the halide is brighter to my eyes, and this is something I appreciate. I also like the shimmer better, I think you can use fewer bulbs for better blanket coverage, and don't have to buy anything extra to make sure the individual LEDs blend well. I also love the daylight look, with noticeable pop, which is easy for me to achieve with the combo I'm running.
For folks that haven't been as successful with LEDs as they would like, I think MH (or t5, or both) is an excellent, tried and true option that is very easy to implement, and won't break the bank.
