I've been using Inge's agecons for a while now and it works flawlessly in my game. I use it to give 10 extra years to adults (and 10 less to elders), but I altered all the age-groups when I first used it. My teens always go to Uni when they've 11 days left, mainly because those extra 4 days increases the age-gap between themselves and their parents and that makes no sense.
Yes, I'd second that - I use it too. I am interested in stories and I like the sims to stick around longer than their 'normal' lifespans, especially the adult life stage which is just too short.