^ This. When I see the word 'sissy' in someone's name (or on a list of interests) on a site that caters to CDs, I automatically assume it's a reference to the submissive/feminized male cross-dresser. And leaving aside any discussion of what that says about societal attitudes toward non-masculine men, femininity in general, and/or women....
I'm of that mind set myself - if you identify as 'A', you can call yourself 'A' if you want to. It's an attempt to reclaim a derogatory term as an identity. But because it is a derogatory term, nobody who isn't 'A' should use it to describe someone. It's usually a minority within a particular group that does so - gay men refering to themselves as [edit](e.g. Dan Savage, to use a well-known example), or trans women as the T-slur - and I most certainly would not use those words myself.