Yes, there is a very large and very interesting variety found in this process.

If we take the all of the variables into consideration, all of the possible ways X and Y can work:

We have (n1)X and (n2)Y for a population of ((n1)X + (n2)Y), the ratio of (n1)X to (n2)Y, the population can increase or decrease, a gestation variable of (g)X that cooperates with breeding potential of (b)Y...

I could go on, but since this is not an attempt at a full research paper, I think my point in this respect is clear, that the potential for variation in reproductive method is huge.

The question I ask myself is just how important is this to humans?

Look at the basic survival methods of the sexes, X and Y; we eat the same foods, breath the same air, and our physiology is the same for these purposes. The only difference between X and Y is due to the nature of sexual reproduction.

I think that it is of such importance, and so basic, that when examining human culture and society it should be one of the main focal points, of any line of examination.