The HQI is the way to go, IMO. The RSM's biggest advantage to me is the flat faces, so less distortion when viewed from the front. But the HQI is an amazing system through and through. The one thing I would still change is the skimmer. It sticks up over the back of the tank, unlike the RSM, which is completely concealed. And it isn't the best skimmer in the world, but it does work. My experience with the temperature says that if you don't keep the outside environment too warm and don't run the lights more than 8 hours a day, you'll do fine. Longer photoperiods will start to become an issue, and an underairconditioned space in the summer will as well.
Good luck with whatever you choose.
--Jim