having worked in the trade for 20yrs i've found both men and women to be equal once trained up, women loose out on the strength side of things but this can be cured with longer bars / spanners torque mutipliers etc, like all jobs there are plenty of people who don't like getting dirty, are too thick to learn , don't want to learn, can't be arsed to learn, don't have a mechanical aptitude, think they will be working on nice easy ferraris all day long, didn't realise you needed to be a multi-talented contortionist, didn't know the pay was so crap for such a demanding(both phisically and mentally) job; etc etc etc
in the end it all boils down to personal circumstance. i would happiy employ female's as mechanics but in 20yrs have only come accross 4 all of whom are no longer in the trade, not due to pregnancy either i may add. two of whom were A1 qualified mechanics and two who only lasted a few months, the two qualified ones left due to harrassment, bullying, sexy comments, calanders, posters, biased employers etc etc etc a shame really.