Dear Sith,
I'm just a simple crossdresser, so I may be making a mistake (sorry if I am) but I suspect that "T" refers to Testosterone? If so, the guy with whom I inhabit this (strongly male) body also takes testosterone and has for maybe 8 or 10 years. It is the fountain of youth drug for him, makes him feel 20 years younger, helps him heal more easily from the bumps and cuts he gets from his lifestyle, gives him an aggressive edge which is important in his business world, and causes him increased sexual desire (me too, since I also inhabit this body).
Testosterone also keeps my guy up and moving, doing the things that need to be done rather than sitting around and watching tv or something. It helps increase "focus", helping him to keep following things through to completion. And it also does away with "the wintertime blues", some sort of low level depression that happens when its cold and cloudy a lot. A marvel drug.
As part of my guy's business world, he often went to a certain office where he was friendly with the secretaries who worked there. One day one of them asked what aftershave he wore. Puzzled, he said he didn't. She said, "come on, I want to get some for my husband". Kept after him over several visits. But he doesn't wear any. Later he mentioned it to his wife and she said "its your testosterone she's smelling". So yes, the body scents change.
Downside? Well its expensive and the insurance companies don't like paying for it. My guy uses the daily "gel" instead of the weekly injection -- he believes that it smooths out the effects better for him. But the insurance companies prefer the less costly injection.
Also, at his prescribed (fairly standard) dosage, the aggression and sexuality can be a bit high. So he often does half-dosages much of the time, upping to full dosages a few days before a difficult event when he needs to be at his best.
I see that Krobinson mentioned that "T does things to me that I really don't like". My guy's body may run different in various ways. First, his natural testosterone level is low when compared to the "standard male population". So his dosage amounts do not "overload" him (and when he feels overloaded, he goes to half dosages). Second, he's a guy. My understanding is that Women also benefit from testosterone (primarily libido I've heard) but they do so at much lower dosage levels than are given to men.
So if you're talking about testosterone, it sounds like its working good for you. It certainly has for my guy. Enjoy.
Caroline