mixed dubs is a very challenging subset of regular dubs. this is because the USTA in its infinite wisdom does not have gender neutral rating system. so a male 3.0 player is not on par with a female 3.0 player. this creates all sorts of unique situations in actual play.
if you play video games a good analogy is that it's like playing super mario brothers and beating the level and then nintendo says, hey now try beating this game UPSIDE DOWN! same game - totally different gameplay.
i find that a cheaper alternative to playing mixed dubs but still getting all the benefits of mixed dubs is to run around your block as fast as you can and then when you get home - punch yourself in the face. i have just saved you a lot of money.