Chuck - great view there!
Personally for me, if it was just a one night stand, I wouldnt disclose. The only time I ever, and unwillingly so, tell people about transition, is if for necessary medical reasons, and when I was starting a relationship with my now ex. Other than that, Im stealth as I, like Chuck, only see myself as male and wouldnt want someone judging me on something I had no control over.
Now, I havent gotten to the point yet where I could go out and have sex with whatever girl, as I havent had the "glans" work done yet, so while I feel my penis looks good, it probably wouldnt pass yet :p
But if I found myself in a situation where I wanted to just hook up with a girl, I dont think Id feel bad not telling her. The way I see it, I spent my teen years knowing who I was, but being so severely depressed that I was unable to be me, that I hardly lived. I saw many of my friends going out and pulling girls. And while thats something some people would disagree with, and its not something I see as needing to do to feel like a guy thats lived a full life, I wouldnt rule it out as some fun that I feel Ive been denied so far. I would never disrespect anyone or treat them badly, so since Im single now, I could see the attraction to do this without disclosing.