It seems to me that, as a point of human psychology, pain and fun genuinely do have different scales. The reason is that the worse pain is more subjectively intense than the best pleasure, which looks to have obvious evolutionary reasons. And similarly our wince reaction on seeing someone get kicked is a lot stronger than our empathic-happiness at seeing someone have sex. So questions like "how many orgasms equal one crushed testicle" are genuinely difficult, not just unpopular. (Which is not to deny that they are unpopular as well, because few people like to think about hard questions.)

None of which excuses us from making decisions in the case that we have limited resources and can either prevent pain or cause pleasure. I'm just saying that it seems to me that our psychology is set up to have a very hard time with this.

To answer the question: For one orgasm, I will trade a few good hard punches leaving bruises. (Observe, incidentally, that this or a similar trade is made many times daily by volunteers in BDSM relationships; noting that there are people who enjoy some kinds of pain, and also people who don't enjoy the pain at all but who are willing to not-enjoy it because they enjoy giving pleasure to someone else by not-enjoying it. Human psychology is complex stuff.) I will not trade permanent damage (psychological or physical) for any number of orgasms, on the grounds of opportunity costs: You can always get another orgasm, but permanent damage is by construction irrecoverable. In the hypothetical where we gene-engineer humans to be more resilient or orgasms to be more intense, the details will change but not the refusal to trade temporary pleasure for permanent damage.

I must admit that I feel uneasy about the above; it seems I'm saying that there are diminishing returns to orgasms, which doesn't look quite right. Alternatively, perhaps I'm measuring utility as the maximum gain or loss of a single person in my sample of 3^^^^3, rather than summing over everyone - another form of diminishing returns, basically. Nonetheless, this is my intuition, that permanent damage ought to be avoided at any cost in pleasure. Possibly just risk-aversion bias?