I've seen it tried here before. At one point there were sub-forums split up into 10 year age increments. One for teens, another for 20-30, 30-40, 40-50 and 50+... or something along those lines.
The teen and 20's forums were hopping and active. Lots of posts. But it was 90% crap, and more mature, experienced guys couldn't stomach posting in there. Younger guys wouldn't listen to them anyway because they were "old". On the flip side, the older forums were dead. Most posts either went without responses or only had one or two, and often, there wasn't enough activity to keep a thread going or enough advice being given to satisfy anyone.
Most people ended up posting back in the general forum as a result, and the sub-forums were pretty much consolidated back to more broad age ranges.
I think the range of age and perspective forces discussion and helps identify what's universal in game regardless of age.
If you really want age/maturity appropriate advice, either put it in the thread title or establish that desire in your first few sentences. YOu'll get more out of it than you would in a dead 40+ forum.
Besides, I don't know about you guys, but I've met plenty of women who may have been 30 years old, wanted to be treated as if they were a mature 40, but actually behaved like a 20 year old. Which forum would I go to for advice on handling THAT? lol