Mixing Page formats and PR

How many people realise, much later in the life of their web site, that a different page format other than HTML would have been a better way to start?

I am wondering what affect mixing page types can have on PR? I have a site that I want to change from HTML pages to PHP pages but am not sure what would happen if I were either -

a. to rewrite and publish it all in one go, or

b. to do it over a period of time (which would be much easier right now).

Does anyone have some experience of this?

Your PR will take a hit no matter what for the first full update of the change. The reason is because changing the file extensions changes the URL and thus All of your internal PR is lost and you start from scratch.

However your results will return very quickly because you dont have to rebuild your source PR on the index (Its already there) so after an update your PR will propoagate to the new pages. I'm pretty sure you can do a 301 redirect on the pages as well to tell Googlebot in the meantime that the pages have permanently moved to a new file extension and that will help out.

The best advice I have, choose a historically low traffic time of the year and make the wholesale change (If there is one coming soon) then ride out the hit for the short period between updates and then you will be back in business
Good Luck

Oh yeah, and if you can do it, make a sitemap on the index for a short period to get all of your new pages included in the index quickly.

You can remove later when they have been deepcrawled

Thats very informative help, I seriously appreciate it, thank you VERY much.

What would maintaining a mixed format do, though? I mean, would it be better or possible to retain the existing PR and introduce new pages in PHP as opposed to the HTML?