I had purchased a Vertex Alpha 170 it had the red dragon pump when i bought my equipment for thr RSR 450. I just sold it recently to another member here and he is very happy with it.
personally and i have used alot of skimmers the atb 840 would be a perfect fit and is probably the best balanced skimmer out, the vertex 180 would be decent also but would need a pump upgrade.
Would bet those vortex skimmer overflows were because of the adjustable air valve on the venturi. Turned out is closed, turned in is open seems backwards, but the way it works. Also think most people think less air is going to lower the water level but the opposite is true. They use italian made Sicce pumps that have a long standing great reputation, and they'r beasts. So much so it's probably a good thing they have air intake control to dial back so you don't strip the water of nutrients completely. They're also unbelievably quiet, comparatively speaking.I just got the new reef life support systems R5-I and I can tell you that it is a beast. Working flawlessly and build quality is top notch. I was looking at the vertex omega but saw so many reviews about them over flowing which was the problem I was having with my cadlights skimmer.
I have a NYOS 160 on my 90G tank with 35G sump and this skimmer is AWESOME! I have had many skimmers since the 1980's wooden diffuser days. This skimmer is by far the quietest skimmer I have ever seen/heard and it pulls lots of black smelly skim-mate