I guess I'm the lone voice in saying that I use a sc150 on my 55 and it's worked great so far. (knock on wooden object)
It's definitely not a Euro-Reef, but my water is pretty clean and nitrates stay below 10.
I have a newer model Seaclone though so I'm not sure if that has anything to do with it. From what I understand the initial production was junk, but they've done some redesigning to alleviate these problems.
I also don't use the sc150 as a HOT skimmer, it's submerged in the sump up to the height of the inside riser tube.
I'm also using it on a tank that's 1/3 of it's rating (which is rated a 'little' high IMO).
I run the venturi wide open so that it gets maximum air volume (I have a bubble trap in my sump so I don't have to worry about microbubblles) and I get some pretty gross skimmate.
It's not like molasses, but it's not clear.
In fact, I think I have a picture.
I will readily admit that there are much better skimmers available, but I've had a decent experience with mine.
The picture is about 2 days after a cleaning on a 55g with a low bioload.