In his comment on my LJ entry of a week ago, youngvanwinkle took exception to my using his real name, saying that his online persona and his real person are two different things and should not be confused, and further that I hadn't met his real person. I don't believe there are enough fundamental differences to make the distinction meaningful, especially when it comes to opinions on subjects in the real world. I may not have met Daniel, by his reasoning...but if I haven't, I've met the effects of his actions and opinions in my life, and that's good enough for me. If he's that different from his online persona, then he's deliberately acting in a manner designed to be objectionable to me, and that's even worse.
My online persona on IRC (which is the medium that he and I share, to my slight continuing discomfort) is different in detail from who I am in real life, but I make no attempt to behave differently in regard to my interactions with the real world there than I do anywhere else. (I'd trade my body for Sheila's in a New York minute were it possible, but that's about it.) If you see me arguing something online, you can expect the same argument from me in real life. If I don't consider someone a friend online, I don't consider them a friend in real life...and so on.
I don't think it's useful or even honest to have one's primary online persona be too different from who one is in real life. To do so only hides one from the people one interacts with, and makes the relationship thus formed one based on false pretenses. That can only backfire, eventually. For that matter, I'm not sure it's even possible, unless one is a superb actor - and then that only leaves one's friends wondering if they're dealing with the real person, or just a fiction?
I'd much rather have real friends than fictional ones.