But it also seems that there are quite a few troons who have saturated their bodies with the E for years who still have interest in sex and can still get (somewhat) hard.
Any sex hormone will boost your libido. Testosterone is obviously the strongest one, then progesterone, then estrogen is the weakest. Most troons only use estradiol, AFAIK, so their libidos should be pretty weak. But that's assuming their testosterone is suppressed, which it usually isn't. 4chan, of all places, has pretty extensive research on this subject. The most common antiandrogen is spironolactone, but this is a relatively weak antiandrogen, and so the troon also needs a high estradiol level to produce less testosterone for the spironolactone to block in the first place. If their dosages aren't sufficient, which is usually the case because these pills destroy the body (in particular they kill the liver) and doctors obviously don't want that on their conscience, so most of the testosterone remains, and the troon retains his male libido.
Spironolactone is most common in the USA, and that's also where most of the rape troon stories seem to originate. In Europe, cyproterone acetate is the more common antiandrogen, and that's apparently a much more effective one at neutralising testosterone (though it apparently comes with the minor side effect of brain tumours, ah the miracles of science). It's also a progesterone, so while it gets rid of the testosterone libido, it'll still add progesterone libido.
Bicalutamide, the DIYer miracle drug, probably has none of these side effects, since it pretty much exclusively neutralises testosterone (it's considered safe for women in basically all situations except if she happens to be pregnant with a boy). The fact that I've never heard of a femboy going on a rape spree supports my completely unfounded theory.
