Very interesting to hear about the experiences of other women/mothers in academia.
Xenia, with all due respect I'm not sure you're in a position to contribute much to this debate, because academia is such a specific profession, and unless you're in it or have a partner in it it's hard to understand the particular challenges. I can tell you why I gave up my (much-coveted) academic job and let my DH keep his though. We had academic posts in different countries, and while that worked for us for a number of years, it was clearly not compatible with having a family. I had a job in an underfunded department; it was a good job but not my dream job. DH on the other hand had a permanent "dream job" in a prestigious and well-funded institution. He loved his job more than I loved mine, so I gave mine up and looked for a new post close to him. I would like to think that had the situation been reversed, he would have done the same for me. Otherwise I would not want to be married to him! I hate the fact that I have joined vast numbers of academic women who have been forced for whatever reason to compromise their careers, but if I had to do it all over again, I don't think I would have chosen any differently. He has made compromises too; he would probably prefer to move back to his country of origin and work as an academic there (and he could probably find a good job there in a heartbeat, as his field is a very popular one at the moment), but I am in a very niche field (that I love) and I would be virtually unemployable in that country. So living in the UK is a compromise that both of us have made.
And yeah, I'm sure the REF is bad for women. Ugh.
TBH I have this fantastic post now, and I'm scared shitless that I won't be able to publish enough to make something of it. I'm going to do my best though. I have more paid childcare than I've ever had before, and I am trying to adopt a newly "selfish" attitude in the workplace that involves saying no to whatever I can say no to and protecting my research time at all costs.
Which doesn't explain why I am currently wasting time hanging out on MN. 
There are some fantastic women academics at my institution though, very inspiring. You are amazing, dreaming, to have forged a path at your institution the way you have, depressing as your story about other women dropping out of PhDs is.
I am also trying to be more strategic about the research areas I choose: to move away from 'niche' topics to more mainstream ones. I want to write stuff that people in my field will actually read. For a change (ha!).