I'm happy someone started this thread, since I've been curious about this same question myself. I'm planning to start hrt in the next few months, but I've already noticed many of the same issues in my own sexuality over the last 3-5 years. My doctor diagnosed me with low T about 5 years ago, & it was hard for me to understand how all of this fit together. I've had issues for years now where it's hard for me to "get in the mood" for sex, & even then it's difficult for me to hold an erection, unless I can really stay focused & keep myself in the moment. I've noticed that even now when I look at beautiful women that I'm attracted to, its more of a desire for intimacy, instead of just a raw sexual desire.
All of this has made my marriage extremely awkward when it comes to the topic of sex. Many times I'm around men or family members who make jokes about sex, or talk about intimacy with their spouses. I always felt awkward, considering my sex drive had a more feminine nature to it, & me and my wife don't really have sex much anymore. None of it really made since until I realized that I'm TG.
I'm not sure what kind of effect hrt will have on me, since I've already having some of these issues, though I'm very curious to find out though. I have noticed like others have said that even though the erections are harder to keep, when you can get in the right mood/state of mind, the orgasms are much better.