Hey Scott,
HOT or in-sump is entirely up to you. It's always nice to have one less piece of equipment out of the display, but then that means more bugs chewed up in the sump/refugium. If you do go for an in-sump model, what about dividing up the sump into two more defined sections, that way at least the pump won't be jammed with caulerpa. The skimmer you are looking at, is there a site with more info on it? Have you thought about an
AquaC EV-90? Or, if you go for an HOT, what about a Remora? The gorg's you have seem to be doing great without very efficient skimming right now, maybe you could even try skimmer-less!

HTH
Drew