My experience with swing keels is limited to the Catalina 22. Gives you a five-foot draft on a small boat, which I liked, but after acquiring the boat (a 1976 model) in 1998, and adding a new cable and winch, the cable snapped twice in the four years I sailed the boat. I had to get in and out of an inside slip with a hump in the middle of the fairway, so I had to check the tides, or hope that I could plow through it with the outboard. I talked to Catalina Direct, a parts supplier in California and learned that I should basically keep tension on the cable, rather than letting it go slack. The whipping action of a slack cable will eventually lead to it breaking.
The other issue was the entry point of the cable into the boat and the system used to make sure water didn't gush in. Kind of primitive (a piece of radiator hose attached by a hose clamp to a "cone" molded in the fiberglass of the bottom of the boat) and I was just never comfortable with this system.