This summer I replaced my AquaC Remora HOB protein skimmer with a Octopus 800s HOB protein skimmer and am very pleased with its performance.
I had the Remora on my tank for a couple of years which produced very light-colored, near scentless skimmate the shade of apple juice. I've always contributed that to the fairly light bioload of my 65gal reef tank (containing four 2.5" fish which I feed every three days).
The Octopus HOB that I have, however, is definately out-performing my previous skimmer. With no change in my system's bioload, the Octo-800s consistantly produces large volumes of very dark (resembling black coffee) and very foul-smelling skimmate.
The Remora and Octopus 800s are the only HOB skimmers I currently have experience with.