as derrida pointed out so long ago, one cannot posit a binary opposition without prizing one inherently above the other. in this case, men are seen as normative an women derivative. now, i am a man, so i can never really know what it's like, and it is good that people are examining this phenomenon with a rational eye...
BUT:
when does reasoning become rationalizing? There is only an 'issue" with coed prayer environments if we are uncomfortable being around the attracting sex. it's our discomfort with sexuality and our embodied natures that makes it an issue. personally, i cannot davven in a mechitzah minyan entirely comfortably, because i know what it does and what it represents. and i am saying that as a man.
now, i am not denying that there is a special quality to davvening with one's own gender, but i am not willing to subject an entire group of jews to second-class status to accomplish that. if there were two services with equal opportunities, then that would be another thing entirely. separate but equal only works if the equal part is true... and (most importantly) it's VOLUNTARY.
this is why i think your endorsement of the mechitzah (as half-hearted and ambivalent as it was) smacks of disingenuousness.
to the above commentator, does it really take the (albeit mild) subjugation of women to make a space a makom kadosh? to me, it does the opposite. what makes a tefilah service holy is (to me, at least) the use of the siddur in the lashon kodesh, a community directing its hearts to God with commitment and intention.