They also tend to try to out-think you. More than once, by the time I think that I have trained one of my girls a new exercise, she has already figured out three or four ways to get around doing it. Females also tend to be more intuitive and aware of their handler's mood. In my experiences, they tend to read my anxieties more accurately and it tends to affect their performances, often for the bad. Mother nature has a lot to say about how you dog will perform whether they are male or female.
Bitches react differently at different times of the year due to their heat cycle.
False pregnancies can change your bitches personality. This is also a concern for your future obedience prospect. It is true that bitches in season can not be exhibited, but unless you train in a bubble, and only attend obedience specialties, it is very likely that, at some point, your male will be 'thinking' with something other then his brain. Of course, there are ways to get around these problems. Neutering or spaying is the easiest solution.