I read Opening Up as well. I asked them both to read it-they didn't. I haven't read the Ethical Slut, but no one's asked me to either.
Maca asked for advice early on, RP's husband suggested he read "Living Happily Ever After". I saw the suggestion, I bought the book. I read the book (great book). I asked Maca and GG to read it.
They both started it (together) but both of them opted to put it down before finishing chapter one and neither has finished it. MIND YOU that was after BOTH of them were acknowledging that there were some KEY things in that first chapter that they each needed to work on!!!!!!