I defend her as the person who didn't ruin BtVS since Joss was ultimately in charge. I see so many people calling her names (largely sexist ones) and directing all their vitriol at her in ways that disgusts me, especially because these are the ones who let Joss get off scot-free. I heartily disapprove of the sexist critiques of her, as well as those who act as though she's entirely to blame for the last few seasons of the show.

I did know that she was using her experience, but I actually don't have a problem with that--writers often use their experiences, including many of their less than pleasant ones. Since the scene was harsh, I assumed she recognized just how awful what she did was and, like you, she just hadn't though through all the gender reprecussions of the switch--I was willing to cut her some slack for being clueless, since that was, in my mind, her first offense. Locating it in a context of all that stuff you mentioned, though, completely changes it.

I'm unclear over whether or not she understood what that gender swap would do to the sexual politics of it.

This is very true, as well.