I know this thread has been dead for a while, but I've been thinking about adding my voice on the subject for quite some time now. So here it goes.
The question is: what is the purpose of the women-only classes?
I met a karate guy who told me that some years ago, his club had more female than male practitioners! And karate clubs/dojos in general have less women than aikido clubs. Two weeks before the regular beginner's course started, they gave a "self-defence" course for women. He explained to me: normally, a woman in a karate class will be corrected by all the guys she trains with... but if she has done a little training before she will bemore secure in saying "no, I konw how to do this". And the guys won't scare the women away.
The interesting thing is, when I met him it was a few years after they stopped doing this self-defence course. What about the women? They were gone.
I think you can make more women start practising with some special efforts like this. If you get any women who stay, that's another issue!
If the women who come to the club in this manner don't stay, either someething else in the club's structure is not well suited for women - or the budo in itself is less attractive to women than to men. Most ladies will then find they prefer doing something else, and quit.
But if you need more members to pay the rent, I think women only classes can serve this purpose. Only beware that they don't become "women can't actually do it the way the guys do it"-classes. But then, if it's money for the rent you are after maybe that is not a problem to you.
If I was to choose between two dojos and one had women's class and the other didn't, if all other things were equal in both places I would choose the one that do not separate the sexes. A few voices here have said the same. Well, we who post here beling to those who stayed...