Hi,
Im an older guy,who only has been wearing for about 4 years.I wear a piece low density,some recession, with truck loads of grey in it.This really adds to a realistic look,as most people don't associate a piece with lots of grey hair in it.This is a dead giveaway,on older guys who sport the high density,dark colour piece.
For you younger guys i would slowly drop density,add grey,and recession as you get older,this is what i would do if i was younger and getting into wearing.Also your friends/family will see your hair changing as you get older,this adds to a more undetectable look.

Regards Topcat.