Messalina,
Thank you kindly for answering my questions. And by the way, you can be certain that I read your posts.

Your explanations are extremely informative; you're obviously very well-educated (not to mention, you have actual experience with the subject matter).
The two events you mentioned do sound grim for so many reasons, but you undoubtedly had a very good reason to use such force. As a man, the idea of any damage to my testes is honestly quite terrifying. Though I've never endured any serious groin injury, the obvious, delicate structure of my testicles as well as their extreme sensitivity to impact and pressure are enough to make me very cautious. It's amazing that Mother Nature made a man's body this way.
In your post, you mentioned that the testicles are "somewhat protected from injury by their placement, behind the penis" and that "someone really has to make an effort to get at them." This is true much of the time as the soft penis can absorb a lot of impact as it rests in front of the scrotum. However, I was just thinking about the irony of male arousal. When a man becomes aroused, his penis involuntarily rises rigidly upward and foreward, leaving his scrotum to hang completely exposed below. In this case, the testicles are certainly very vulnerable. It is just amazing to me - almost as if it was one of Mother Nature's ways to discourage ****.
Perhaps I'm straying from the main topic somewhat, but I've come to believe that the vulnerability a man exhibits (due to his vulnerable genitals) while having sexual relations with a woman is a beautiful thing. Most women probably feel somewhat vulnerable due to their natually inferior size and strength, but women have great physical power when it comes to sex because a man has to let his guard down. Thus, sex is always based upon a kind of trust. That's really wonderful; I think.
Thanks again for all your posts, Messalina (and to all the other women here too)!