I have a 90, and I love my Avast CS1 in recirc mode with a swabbie. I don't have much opinion on the skimmers themselves, i've read some skimmer test articles that supported what JPMagyar said, all skimmers take out the same "stuff" and they do it within a couple hours, some just do it a bit faster than others, but in the end they all reach the same stopping point. The articles i read also showed that the time differences were at the tail end of skimming, they all removed something like 90% within a very short time (all roughly equal), then some were just a bit faster to get that last 10%.
My experience is that having a regularly cleaned skimmer neck has greatly improved the skimming because the stuff that used to get stuck on the neck between cleanings now goes into the cup. I haven't seen anyone talk about it, but it seems to me that crud that collects on the skimmer neck is still in the water and is still going to rot and release phosphates and nitrates back into the water. IMHO you need to get it completely out of the water column to prevent that, collecting it up on the skimmer neck isn't enough. No matter what brand skimmer i have in the future, i'm always going to have a neck cleaner, not just to simplify maintence, but also because i can see a water quality difference too.
