I do seem to recall that there was a historical precedent in the Roman Empire where supposedly some of the gladiator slaves in the Coliseum were penectomized but left with their testicles. Supposedly the idea was that they would be more fierce as fighters (due to frustration?) but not have the loss of muscle mass that would have gone with removing the testicles.... I believe they were still called eunuchs, despite still having balls....
Personally my approach to use of the term is that in person and related contexts I present as straight male, and don't discuss things beyond that - I let people believe what they think they see....

I also keep the "M" identifier on my drivers license, passport and other ID documents.... My reason is that the biggest reason I'd be showing them is to keep some government official happy, and I'd rather not trigger any biases on the part of "Officer (not so) Friendly" that might make him inclined to make my life more difficult than it is.... I want the cop to decide that I'm not the droid he's looking for....

WheelyFixed