I'm about to say something you've never heard a science fiction writer say about fans before.
Relations between science fiction pros and fans have always been conflicted. There's no denying that fans are useful, what with all the conventions and awards and such they organize and arrange entirely at their own expense. But there's also no denying that they're not very subservient. Just talk to one! They clearly think that their opinions are as good as yours. Worse, because they've read so many books that often they have an array of facts to back them up.
Muddying matters, many SF writers -- possibly most -- started out as fans. Whence the venerable fannish term "filthy pro" derives -- as in, "I hear you're a filthy pro now." It's affectionately meant, and always has been.
Further muddying matters, fans have never been reluctant to let us writers know when they think our work sucks. Repeatedly. Over and over again. As if we hadn't heard the first time.
So my take? It's this. A typical science fiction fan will subscribe to at least one science fiction magazine and possibly more, will read several SF novels during their year of publication, will purchase at least one of the Year's Best volumes and read through it, and will follow several online fiction zines.
Which is to say that she or he is as informed and literate a reader as any writer could hope to have.
But you didn't hear that from me, okay?