I would suggest going with your initials, as that appears to be an option "within the rules". I too was concerned with the "full name" showing, particularly as usernames are present and somewhat of a de-facto convention online.
A reason often given to support "real name" policies is that it promotes civility. I would argue that not only is this an argument made without good supporting data, but that effective alternate measures (removing comments, blocking IPs) are available that do not have the side effect of discouraging speech.
As this site is indexed by Google, threads often turn up prominently in search results. I accordingly take care to tailor my (few) posts for a wider audience. This means that items I might discuss more casually with friends or colleagues are "sanitized" for a much wider audience, or most often simply not posted.
The ability to post pseudonymously allows posts to be accounted for on their own merits, and provides a modest buffer against those who may take offense at the contents of a seemingly innocuous post. At a further extent, what may be a normal and appropriate comment in one area may be a prosecutable offense in another. More probable is the chance that sensitive negotiations could be affected by prior posts. (One may assume that anyone involved in such would have the good sense not to live-blog such deals.) In an ideal world, we could all speak our minds without concern, but the sad truth is, many countries, businesses, and people do not respond well to criticism.
Quoting from the second link below: In the midst of the civil rights movement, the NAACP challenged an Alabama statute requiring the organization to reveal the names and addresses of all its members. While ruling unanimously in favor of the NAACP, the Court avoided any explicit recognition of a right to anonymous speech in favor of an alternative, more general constitutional theory. The Court noted “the vital relationship between freedom to associate and privacy in one’s associations.” (Emphasis mine.)
Additional reading: (the first not too long, the latter more comprehensive and semi-tangential)
The Curse (Blessing) Of Anonymous Speech
Publius and the Petition: Doe v. Reed and the History of Anonymous Speech
ed: added hyperlinks