I have been reading articles found on the web about how changing the content on your site instead of adding it, can potentially damage your SEO, despite even if it is about the same subject, using the same keywords.

 

I know there is such a thing as domain age and page age. What about content age? or is this a load of rubbish?

I think it's a bunch of arse to be honest. Of course, provided you are improving your content, and not just making it spammy in an effort to climb up the SERPs, then I would suggest that a positive impact will be had in SEO terms.

I agree with notbanksy, fresh updated content is always good although obviously it has to be on topic ie relevant generally to the rest of the content of the page but to be frank just write about stuff your visitors will expect to find on that page and what they will want to read and you should be ok.

Yeah agreed sounds quite silly.

 

But - you may find rankings drop initially (sometimes quite sharply) after changes, usually they are placed higher after being indexed again if they are optimised better.

 

http://www.seoibiza.com/blog/2009/02/13/seo-experiments/

and

http://www.seoibiza.com/blog/2008/05/25/seo-experiments-google-950-filter-in-action/

 

make an interesting read. On the whole though, if you are doing things sensibly you won't get penalised.