Hey here is an example of a Magento site where all pages (even statics like About-us) have been moved to the flat .html extension (example: http://www.topdjgear.com/about-topdjgear.html/)

In my opinion it is best to present a uniform URL structure sitewide and generally flat HTML files are a good thing although I also have worked on very successful eCommerce sites that used no file extension.

It is relatively easy in Magento to mod you static page to include the file extension, so in terms of lowest barrier, this is the route I would go.

I'm extremely interested! Not directly through age, but it's in there - IMO it is more so a relative measure of the ability of pages on that domain to rank for a keyword versus a stand alone metric for measuring rankability.

A couple questions if you don't mind sharing:

1. Has the domain been previously registered or ever had an indexed URL on it in the past?
2. What is your daily crawl rate according to webmaster tools?
3. What is you new URL to indexed URL ratio?
4. What is your website's SEOmoz measure of p-links and d-links, and how do these stack up to the the averages of the top 10 URL's currently ranked for your primary anchor text keyword phrase?

More data makes for more interesting conversation. Thanks in advance.

Well, actually DA is very relevant to what I want to achieve - I want the ability to build marginal page authority and still be able to rank well in a relatively short period of time. Based on my research, and I have a lot of it at this point, DA that is comparable to the average DA of the top 1o currently ranked URL's for a particular keyword enables pages with PA of sometimes 1 to rank within the top 10 - which is precisely what I am attempting to gauge.

There is absolutely no way DA can be increased by anywhere close to 50 in less than 6 months. Regardless of where your links are coming from it is made quite clear that this is largely a measure of trust beyond relevancy and must be built over time.

I understand that it is easier to rank for a particular keyword given a higher DA score. How fast can  page authority be established and grown for a given keyword if DA is equal to 10/20/30/50?

What are the relative measures that dictate the establishment and growth of this authority? Can it be enumerated to a percentage of domain links? or a percentage of domain links given an assumed C-Block ratio?

For example you have a website with DA of 40, and you want to target a new keyword, the average PA of the top ranked pages is 30, the average domain links are 1,000, and the average number of linking domains is 250 - if you aim to build 1,000 links per month from 500 linking domains, how fast can you approximate the establishment of page authority for the keyword?