You could also consider the SC Aquariums 120g or 150g plug-and-play system for maximum "footprint" flexibility. You can opt to have them deduct the skimmer and return pump (I would honestly, canopy too, but others might use it), and remove one of the baffles in the sump to better run a refugium/ chaeto chamber. You would basically have to provide lighting, return pump, skimmer. ATO, heaters, and circ. pumps - basically doing that with the Red Sea aquariums anyways.
Not necessarily stating this would be a better option than the Red Sea systems, but something else to consider. I personally don't like the Red Sea sumps, as I like the room to grow a bunch of chaeto for nutrient reduction, but if one didn't, then that might not be an issue. I go back on forth on the cabinets too...
