Im apparently one of the very small majority of people that like their seaclones.
I use a seaclone 100 on my 20 gallon tank and it does a great job skimming. One of the 2 LFS in my area uses the Seaclone 100's on every salt tank in the store, and they really skim something fierce. Everytime I go in there, they are really bubbling out some dark skimmate.
I've now resolved that a skimmer will skim when there is something to skim.
For example, if I overload the system with proteins (like when this tank was a puffer only tank and I would feed them a jumbo raw shrimp), then the skimmer would go crazy and start producing masses of wet skimmate, but now that the puffers are gone I only feed krill, mysis, brine, small things like that, and it usually kicks it on to start skimming, and when it does it produces dark brown skimmate, almost black.
So... If you can get one at a good price, then I believe they are well worth it. But if you have the extra money, then go for a remora. But again, I believe the skimmer will skim, when it's got something to skim.