This made me wonder why Carnival didn't bother me *more* - I think I read the argument as "socially constructed roles based on genetic features suck," not "patriarchy sucks." Thus, it didn't bother me that women were unhappy in a society with strict gender roles - even if theirs happened to be powerful (and any group could be justifiably worried about the ethics and sustainability of oppressing half the population - I didn't read "afraid of ruling over men" as a negative, Pretoria's situation in particular seemed like "I would like to support them, but don't really know how, from my privileged position, to do that" - maybe that's because condemning feminist guys in the real world as "afraid of ruling over women" really, really disturbs me). Vincent and Michelangelo are operating outside of their strict roles, so they come off as more free/better in the window of the novel - but viewing sexual orientation as an innate trait, their socially constructed role based on that is outcast, which didn't work either.
And the very-not-human alien species does have social roles based on genetics, which works for them, precisely because they aren't human.
Incidentally, somewhere in her blog, she mentions that Carol and Autumn (lesbian couple from Whiskey and Water) have the most healthy relationship she's ever written. Wish I had a citation, but I stumbled on that a long time ago.
Sorry for the length of this, I've been on a Bear kick lately, and the thread was fun to think about.