I just wanted to relate what happened in New Zealand—this is my understanding—when they introduced MMP. More women got elected, no doubt about it, but guess what? Power does not lie in parliament. It lies in the cabinet. Fewer women ended up in the cabinet because you had a trade-off among the leaders about how many cabinet posts each party was going to get and they were going to get to decide who's in them.
Right now there's pressure on the Prime Minister to have a diverse cabinet, but the pressures will be completely different when you have horse-trading among the parties.