Well, it depends who exactly the brony is. I don't give out anything personal online unless it's for a purchase or something, but seeing that my identity is nearly completely anonymous and I can control what others know and don't know about me (never link any accounts for anything together!), then I find that the internet is safer than most people think it is.
I don't trust anyone online enough to give my address or anything, but as with problems or secrets, sometimes it's good to talk with a stranger about the former, but the latter should only be talked of with trusted friends. I posted this on a different topic, but speaking with strangers (not the type you're thinking, ones on sites like this) can often be a good solution to things. Since they don't know you at all (and if they do, very little), they can't judge or base anything on you, meaning they at times give honest from-the-heart advice, whereas people who've known you for a long time will give you what they think you will like most or something similar.
But hey, this is only what I think. I only place trust in those that I know won't betray me.