I had a Reef Devil II. I felt it was a waste of money. I paid something like 250.00 new about 6 years ago. It never skimmed good, when it did all it took was a hand in the tank, food in the water, openclose a window, dust the furniture, fart in the room and it would stop doing what little skimming it did. I played around with different pumps, gate valves, Beckets head, what ever I could to get it work. I canned it for a Euro Reef skimmer. Compared to the ER the Reef Devil II was a door stop.
I'm sure others think its the best skimmer in the world, until you have a good skimmer to compare it to.
I've seen the bigger ETSS skimmers in action. They seem to be very good. I'd NEVER use one but just like lighting what ever your using is the best.