Currently, being "openly transgender" means that despite rarely being perceived as male, I am out to everyone I know, ask them to use proper pronouns, and discuss trans-related things as casually as anything else. I also blog, attend trans* groups (when possible), and engage online with many other transgender people.
In the future, it's likely that I'll develop "passing privilege," at which point, I will still openly discuss trans* topics, engage in activism, and discuss my own gender under similar circumstances to now, only instead of being initially read as female, I'll be read as male initially.
For me personally, I have never intended to go "stealth" because I want to contribute to improving the climate for transgender people. I'm also one of a very small number of transgender academics, and it's important to me to be an open representative of this demographic, and to encourage transgender youth to consider academia as a career path.