The average xbox gamer is between 12-18, while the ps3 is 24+. I don't know what the average PC gamer age is, but I would guess mid 20's, because like the ps3 price plays a role in the average user base age.
It would vary depending on the game.
My experience (though this is probably not reflective of reality) in communities, be it clans or just groups of people, ranges. I have been with people who are 15, but then I have also been with people in their 70's-80's. The upper end is very rare though, the majority I have played with have been, at the youngest, early 20's, and the oldest mid-late 40's
Hate to use this example but.... I believe it was Halo 2 that there were numbered ranks. You do crappy on a game or lose a game, your rank goes down. You don't get points just for playing online. Basically there are ways to get around this but for the majority of it, you were skilled at the rank you were rated at. This combined with matching with your rank number, would work wonders.
OK, this is why I don't see how it would work:
I am decent at CoD4. Throw me in a public server and I can easily beat 5 or 6 people on my own no problem. However in a full game wither at least 8-10 per side at a minimum, I generally am not as good as I am when alone because I find myself depending on others, getting let down by others or getting overwhelmed. As much as I can handle myself, I am not a god
.
It is for this reason that if you are in a lower rank than you should be, yes you will find compared to others you will be better, but you will also find that you are trying to 1-man-army a lot of the time because team mates are useless.
Now I am sure that there isn't the potential for a system that will work and I will admit now, I haven't played Halo, except for 1 on PC and about 2 hours of 2 on Xbox , so can't say if it did work well, but the ideas put on the table thus far haven't worked because people always get stuck at a lower rank than they deserve and find it an uphill struggle unless they play every game with friends who are also skilled.
More on topic, everyone that has MW3 in my clan has the same point of view as I did (these are people that bought the game...), it is MW2 with some extra tat stuck on. Glad I didn't buy it or even look into it other than playing the pre-release