I've used ASMs, Euro Reefs, BKs, remoras, urchins, bubble magus, seaclones etc etc...
In the end, your (insert $$$$$ here) skimmer gets covered with fish crud. Have I noticed a difference between ASM and BK? Not really. ER and BK? Not really. Bubble magus and BK? Not really. Remora, seaclone, urchin vs. BK? Absolutely. Those three skimmers are pieces of ****.