When I dabbled in Pern fandom, that was also dominated by women. In role-playing games I usually played male characters, because there weren't enough men to keep the game balanced. The Pern track at Dragoncon has a lot of cosplay, and a lot of focus on the culture of Pern. But it's really not much different from the male-dominated (at least it was before the new movies) Star Wars track with its Stormtrooper Legion.

The main difference I see between the Pern and the Star Wars fans is that the Pern fans tend to see their fandom as a living entity-- a real culture that they can adapt and play with. Star Wars fans tend to see their world as more static, well-defined. Even many Star Wars role-players aren't so much trying to make their own characters as trying to recreate "historic" Star Wars events. This difference could be because of the dearth of approved Pern role-playing materials compared to Star Wars source books. Or it could be because women tend to be more creative, men more analytical, if we want to focus on gender.