Downsides of mixtes were how I finally convinced my wife to go to a standard frame for her latest bike:
- On hanging type automobile bike racks, often annoying and/or harder to hang with other bikes
- Harder or impossible to have two water bottle cages on top of down tube.
- Harder or impossible to use frame bag.
- You never wear a skirt riding, anyway.
- Men's sensitive parts are more a risk from a closer to horizonal part bar.
- Many if not most modern frames have "sloped-enough" top bars anyway.
Later on I upgraded to a platform-style rack and my wife said "Hey, wait a minute..." but by then she realized she liked the new bike better than the old "girl's bike" anyway.