In my experience, there seems to be more female centered V's or other configurations who are active in all aspects of the social poly scene (both online and local community groups). My assumption tends to be that there are two reasons behind that: the first, is that I'm assuming that the women are just more likely to engage in these forums and that there's a hidden group of men out there that aren't as active (or not active at all). The second assumption is that men are more likely to stay (longer), or more likely to see no reason to change, a cheating situation - which I tend to view as more traditional in the context of what's expected. So, these leads me to believe that there's under-reporting problem combined with men being more likely to be "locked" in a cheating frame of mind.
However, formal, non-monogamous marriage proper seems to be more popularly polygynous versus polyandrous. That, I assume, has more to do with the typical religious basis of such unions that also have male-centered dynamic to them.
<<All of the above assumptions are likely skewed by my background and limited perspective. So, I understand they may not reflect a broad reality>>
On the whole, I agree with NYCindie. Hold any assumptions about relationship structure very lightly. Instead, connect with people that you are interested in and let things play out. You'll give yourself a lot of frustration by trying to create a specific situation. I think this is exactly why so many couples seeking to expand their marriage find so much grief in the transition. They have too rigid a view on what they are seeking. And, contact with reality always screws that up.
Male, Straight, Poly
“Instead of getting better and better at avoiding, learn to accept the present moment as if you had invited it. And work with it instead of against it. And making it your ally rather than your enemy.”