The so-called "rabid nature" of fans has died down significantly over the last couple years. Most fans merely loved the show and got excited about an underdog cause. I know that there are those whose perception of the show and Browncoats has been forever tainted by bad experiences during the height of the fandom. I think that's sad, because now, in a perfectly reasonable thread asking for opinions, apparently some folks still feel the need to "warn" people that the fans are crazy and scary.
I met some of the neatest people through being a Firefly fan. And I have NEVER seen a fan behave in anything beyond a sincere excitement and desire to share the show they love with others.
I'll tell you this, too, you'll never meet a more gracious bunch of celebs than the Firefly cast & crew. They're all awesome.