the etss is in sump or can be run external with the pump in the sump and the skimmer out of itand plumbed back to it.
I dont know about the asm's, but I just got a reef devil and I love it. The asm's use a different technology so I dont know how they compare. When I searched( for many days) I determined that the reef devil deluxe was the best for the money...IMO