I think you need to think about the impact on politics and not just those who are or who are not elected to the shadow cabinet as a result of a quota of this kind. Westminister politics is still very male dominated and experience from other countries suggests that quotas - as a transitional mechanism - can help break that. There were many complaints too of how much the election campaign was dominated by men.
I think a 50-50 gender split in the shadow cabinet would be really good for politics - both in terms of how politics is done and also the policies that are deemed important. Of course it doesn't follow that all women will do politics differently etc but the evidence suggests that when women create a critical mass it does begin to change things. It would also mean more women with front bench experience so that when Labour is next in power there should be more experienced women who would be potential cabinet ministers.
Can I say at the outset, I have no objection to female shadow cabinet ministers, indeed it wouldn’t bother me if the majority were women, however on the condition that they were the best people and not simply there because of quotas or pandering to public bias. The Labour party already uses women only selection in some constituencies to ensure a fair number of women will have the chance of getting elected. However once they get there then the rest should be decided on merit. If the women elected to the shadow cabinet on quotas, were not up to the job, then what is the point of putting them into the cabinet, come the next labour government?
The election campaign itself was dominated by the presidential approach, the stress being on electing a PM and not a party, concentrating on the three male party leaders and more women cabinet or shadow cabinet members would not have altered this.
I am not convinced that more women in the cabinet would lead to more caring family friendly cabinet, the people, men or women, who get into these positions, are usually very ambitious, self driven people from privileged backgrounds, with little real sympathy or understanding of the needs of ordinary people.
I know nothing of what has happened in other countries and you may be right but I just have little confidence in so called positive discrimination, which really just picks out another group to be discriminated against. I can see the point, in the police for example of deliberately recruiting some, black, Asian, Chinese or gay officers to work with communities, who mistrust the force or have difficulties with English.