Male to male instruction can be very helpful in that you will get a very good sense of what a good lead needs to know. It will give you an upper hand on the dance floor and you will not deceive yourself about your abilities.
The male and female instructors are both proficient at either role but, it may be beneficial to you to get feedback from someone who is typically a leader on the dance floor. It can help give you a feel for what the follower needs from a leader, and how a good, clear lead feels. You will learn to tell whether you are in fact "leading" (truly giving your partner the signals she needs to move in the direction you want), or just doing steps and expecting your partner to know where to go.
I say this because I have encountered some wonderful, excellent leads, and then I have danced with leads who think they are better than they are and dance as if I can read their mind. You can be a great lead without having to be a very advanced dancer. The steps will come.
Also, in Argentine tango, it was common for the men to practice with each other when it was not yet a socially acceptable dance and women partners where not readily available.
Hope this was of some value to you. Enjoy.