A mixte frame won't be as stiff for hard acceleration so the performance of the frame will feel sluggish. But some men ride mixte frames because they have problems getting their legs over other frames due to various health or handicap problems. Shorter legs have nothing to do with it because you can get regular frames that are built small for that purpose. And you can't find a high quality mixte frame unless you buy custom, only one production bike I know of that is made decent is the Soma, but all the vintage mixte frames were cheaper tubesets and low cost components.

I was being sarcastic earlier.