[Doubledown]

Let's assume you are looking to run this as an SPS dominated tank.

Run the Eheim as your return for the 120 and supliment with either a closed loop or additional in-tank circulation (Tunze for controllable/directional flow or maximod for unidirectional flow on the cheap). The 1250 will provide plenty of turnover through the sump and will keep up with the H&S skimmer (as you already know). No reason to buy another when you already have a solid pump now.

I like the SLS HQI ballasts that I have, but if I were to buy them again I would go with the Galaxy ballasts and run single ended bulbs in the lumenarc mini or the lumenbright reflectors (over a 24" wide tank). If you will have a hood, go with the lumenarc minis as this will save you space for the actinics. The Galaxy ballasts are an electronic that will overdrive the bulbs a bit and there are many more choices for K ratings in the single ended bulbs. 2x250 will be plenty for the main lights.

There is still some debate as to VHO vs. T5 for actinic supplimentation. Some say VHO still outperforms the T5, but you can't argue with reduced wattage usage. I have VHOs and would buy them again.