I think you're making some generalizations.
I am full time, and it's made my life much easier. I'm transitioning on the job, at church, everywhere. I'm not completely passable or stunning in anyway, and I get called "miss" and "ma'am" everywhere I go. I figure it's part passing and part people humoring the presentation.
Of the FTMs I know personally (through church and/or the Transgender Parents Support Group), none are living as butch lesbians. They are living as the straight men that they are. If that's how they identify themselves, who can say otherwise?