I've had a Herman Miller Aeron at work for 4+ years. I really like it, how the meshy material breathes when I've been sitting in it for far too long, and boy it sure looks cool. But I'm not sure that it's made much of a difference in my posture. I've adjusted all the controls, even watched the "Proper Posture" video they have on their website, but I still do horrible things like sit cross-legged in it, slouch, etc. I think it comes down to your willingness to commit to a proper egonomic regimen. I'm lazy in that way.