Take it for what it's worth as I've not had the magical Google Analytics that determine age of visitors on for all that long (a month-ish), but if site traffic to TheMetalBikini.com is any indicator, the biggest demo for X-Wing, or at least those who seek out more info or whatever, is the 25-34 demo. 35-44 is a relatively close second, 18-24 is an extremely distant 3rd, and 45-54 is just a touch behind the the 18-24 crowd.
Now again, this isn't necessarily indicative of the actual players of X-Wing, not saying it is, etc., etc. Just thought it was interesting that the collective observations of this thread's participants more or less mirror what I see on the site.
Oh, and I just turned 40 by the way.
And I think those demographics are pretty typical. I just want to encourage people to remain open to bringing younglings into the fold.