When to include / exclude old urls?

Hi

I have several forums using vBSEO and the sitemap generator.

My question is, when do I include and when do I exclude old URLs?

Currently my forums (newly started or long time established) all include old urls in the sitemap.

Is there a downside besides the bigger files?
Should I uncheck "include old forum urls" on my newly started forum (1 week old)?
When can I exclude old forum urls when running a forum which got vBSEO over a year after it was started?

Please advice

If you're a new site, there's little reason to include old url's.

I suggest not including them once you get a couple /new/style/ links in google.

You mean exclude them once a few mod rewrite urls show up in google index?
But then the option would not be needed at all.

Is that an educated guess or what is the reason behind this suggestion.

What is the reason for this function anyway?

Personally, i NEVER included them.

the reason to include them is if you're indexed ok before vbseo, you'll have a lot of showthread url's in google. if you suddenly tell google 'here's my sitemap' but it doesn't have urls that are in it's index, it might get confused, sandbox you, etc etc whatever they do...

its ok to include them, because they are 301'ed to the new content, so it's just a matter of time before google indexes you properly with the new url's.
And once that start happening, there's no good reason to keep telling google about your old content, as there's a good chance it's seen the 301 to the new style already.

I would no longer recommend using this feature.