I'm concerned (morally horrified as well as convinced of factual error) by quotes from two texts that are part of the "canon" here. The first advocates nonconsensual sadism; the second advocates sadism. Warning: SEX AND CONSENT AND SADISM TO BE DISCUSSED:

From "Three Worlds Collide":

The Confessor [, a rationality expert on a starship's crew,] held up a hand. "I mean it, my lord Akon. It is not polite idealism. We ancients can't steer. We remember too much disaster. We're too cautious to dare the bold path forward. Do you know there was a time when nonconsensual sex was illegal?"

Akon wasn't sure whether to smile or grimace. "The Prohibition, right? During the first century pre-Net? I expect everyone was glad to have that law taken off the books. I can't imagine how boring your sex lives must have been up until then - flirting with a woman, teasing her, leading her on, knowing the whole time that you were perfectly safe because she couldn't take matters into her own hands if you went a little too far -"

Nonconsensual sex is generally illegal and is obviously harmful, given the widely known, well documented negative consequences that I will not enumerate here. The quote about this is a transparently gender-reversed claim that the risk of sexual assault improves relationships by making them more exciting. This is obviously and offensively wrong. Does the risk of robbery improve living conditions? Does the risk of death improve life? Also, a future society where consent is optional appears to be a terrible dystopia: assuming a free democratic government, lack of consent implies that advertisers and corporations could force consumers to buy things. This quote needs A LOT of additional justification and qualification (and ideally deletion) to avoid implying that "raising the sanity waterline" means "abolishing liberty and ethics."

From the April Fool's Day 2014 Confession:

I’m very worried, in retrospect, that they all managed to cure themselves via standard self-modification techniques. It’s very obvious that if I’d realized in dath ilan [, an ideal rationalist society,] that I was a sexual sadist, I would have treated this as an error and probably not told anyone before I fixed it. It would not have occurred to me that sexual masochists were a thing or that I could find a willing victim to be sadistic at, I would have thought I was being sick and selfish.

Consensual sadism is (usually) legal. For the rationalist goal of "raising the sanity waterline", being consensually sadistic appears to be a distraction at best. Inflicting pain for fun appears likely to harm empathy and sociability. I don't know much about this community/practice. "Willing victim" implies victimization in a negative sense, while BDSM is intended to be positive for all participants.

Moral relativism awareness notice: I am aware that "should" cannot be derived from "is", and that no one knows how or why anything exists except in relation to other things that exist.

Given that we're trying to be "rational", which presumably means "think in a way that gets the best outcome for the thinker given the situation and the available information", I fail to see how sadism is anything but a harmful distraction, and sexual consent an essential good.