In my personal experience, many of the people who think they're capable of polyamory are not honest with themselves, and once a partner starts seeing someone else, they experience bad jealousy which they're uncomfortable admitting, because after all they're not supposed to; they're poly!

This is true. Poly requires excellent communication skills to pull off successfully, even more so than ordinary relationships. I keep emphasizing that poly is not for everyone: not only because you need to be emotionally suited for it, but also because it often takes much more work than a mono relationship. For most people, poly is hard.

Captains of football teams and cheerleaders as the primaries. The rest of us, gazing adoringly upon them while we wait for our turn on Tuesday night. Then back to the romantic ghetto.

I've heard this claim before, but I can't help feeling that it's still thinking in a mono pattern even while trying to think about a poly world. The whole point of poly is that X dating Y doesn't necessarily make either X or Y unavailable to others. If the captain of a football team has five women, that means that he only has one-fifth as much time for each of them, meaning that they're likely to be available to others as well. And perhaphs, since they're getting their desire for high-status übermasculinity satisfied from him, they'll also be more open to relationships with less masculine and lower-status men.

There are plenty of imbalances in dating-related gender ratios. A large fraction of men prefer women younger than themselves, so a straight man in his twenties faces competition from not only men his age, but men in their thirties as well. Add to this the fact that there are more men born than women, and we find that in a mono world a lot of young men will necessarily be left without the kind of a mate they'd prefer. In old age, the pattern reverses, so that it is the old women who have a hard time of finding a suitable partner. All of this is inevitable in a mono world, but in a poly world, there's at least the possibility that everyone will manage to date the kind of a person they want to be dating.

Polyamory is a better arrangement for young non child-producing couples than for people who want kids.

I'm not entirely sure about that one. Raising kids takes a lot of time and effort, often leaving the parents exhausted. It might be better for everyone involved if the kids have (say) three parents instead of just two.