Domain age importance?

Just how important is domain age as an exclusive factor? Let's say a domain of four years old, is there any way to determine the impact of that? Keeping in mind that the site niche keyword is in the domain with regularly updated content, on-site SEO done and a constant process of off-site SEO as well. I'm not really talking about EDM or anything like that, just wondered how the four year period would impact it as oppose to the exact same site, same content, same seo with a very new 2012 domain?

domain age of your optimized website holds more importance rather than a plain old website. If a 4 yr old website's homepage or landing page content and on page has been done recently, then it is as good as a new website though an entirely new website will take more time to come up.

Age gets you authority, and authority gets you PR. My experience is that having a 4 to 5 year old domain will give you a boost in the SERPs because of increased authority, and help your pages gain a rank or two (until you get to PR5) over a new site, if all other things are equal.

Which they never are.

I have not had an issue with a year or two old website ranking higher than older websites. Like the previous poster said, there are too many factors to consider.

Having it is ideal, but not having it is not going to kill you.

An aged domain with crappy content and/or backlinks is pretty much useless and irrelevant. What you actually do with that domain, or what has been done with it before, is what really counts in search engines.

If one would develop and update a domain with proper content constantly over a period of time, then yes, the age will be relevant for that domain and makes it more valuable than a fresh one in the same niche.

Obviously, this does not make it a rule. Take CNET vs The Verge for example; the latter is younger than the first one but they both offer value to the reader. Also it is very possible that The Verge will outrank CNET on a given topic, thanks to all the magic behind it.