When it comes to skimmers I do not try and skimp and go with the best.....
A Sea Clone is the only way to go.......
My next choice would be a coralife super skimmer. If it removes good dark black brown junk continually, and water parameters check fine, corals all do great, fish are healthy, I just can not see what is gained by throwing more money at a skimmer that costs 5x the amont a CSS does.