As funds allow, I would invest in a much better set of reflectors as well. I started with parabolics too (batwings). You have absolutely NO IDEA how much light is wasted and not better directed down into the tank. I didn't believe all the hype at first, but once I bought the reflectors I was sold. I can grow SPS on the sand bed if I want. If you want to stick with the 400's, you may be able to avoid the heat issue by getting the right reflector. The Lumenbrite and Lumenmax Elite Reflectors are meant to be hung much further from the water surface or they'll scorch and bleach corals. When placed too close they create a beam of light. I have the Lumenmax Elite reflectors and they are 16 inches off the water. The picture in my avatar is of my new 195 SPS reef that is coming out of its' cycle now, so the water was hazy when it was taken. There are only two halides over this tank, which will have 60" VHO's as soon as someone has them in stock:debi:.
Anyway,, with some creative aquascaping, you can see that the entire rock structure was cheated in toward the 4 feet in the middle of the 6 foot tank. My tank is Eurobraced so there are no dividers running from front to back like on a stock 125. Regardless, if you don't feel you need 6 feet of intense lighting there's no rule that says you have to use 3 halides. This in itself cuts down on electric and heat for me and I never need a chiller. We have moderate to cold winters in South Jersey but our summers can be extremely humid with temperatures reaching into the high 90's and sometimes triple digits. My water temperature has never run over 82 degrees with a 7 hour halide photoperiod. This is why I aquascaped the tank the way I did. More room for fish and corals to grow, no need for a 3rd halide, and designing a system that I could use a reflector that can still pound the light deep into the tank from a higher than normal distance.
I'd say keep the 400's, get a set of used, cheap Lumenbrite Mini's from someone that's switching to LED and be on with it. You may be surprised at how hot your tank "doesn't" get.