I'm hoping that it will run much cooler, so far it's dropped my water temp by 2 degrees. The real test will when May comes around. On the other tanks, the water temp definitely dropped by about 3 degrees when I switched over in August & September.
IMHO, the best lighting for growth & visual appearance would be MH so by changing over my overall objective was to reduce electrical consumption and reduce heat generated. In the dead of summer, I was averaging daily 110 kw which is a bit overboard for consumption. As you know, the tank with the MH would heat up and kick on the chiller which in return would heat up the fish room etc. Multiple cooling fans would be on 24/7 including the inline exhaust, chiller would be active from April till November.
So overall, LEDs over the 120g makes sense in terms of electrical consumption. It will reduce electrical consumption & should assist in the heat generation department which will add to the consumption use. The Solaris fixtures over the other 2 tanks won't save me on consumption since the fixtures pull more juice then my previous T5 setups.