newsbin.com

I am considering upgrading from 6.41 to 6.70. If I do, do I need to delete and download the headers again?
Anything else that I need to be concerned about?

Dex tells me the headers are the same but the download, wish failed and files lists will probably be list during the upgrade.

You can make NZB Files from the download, wish and failed lists and then re-import them.

I have a vague recollection about needing to download headers again per the release notes in one of the versions, but I do not recall which version. Are the release notes for the different versions still available somewhere?

EDIT: I found some version history here: http://www.afterdawn.com/software/version_history.cfm/newsbin

It states: "When downloading headers, all the updates are sent to a common folder and not "per group". "
Doesn't that mean that I would need to download the headers again?
If I download headers again, will I loose "Downloaded Status"? New vs old?

It states: "When downloading headers, all the updates are sent to a common folder and not "per group". "

No, it just means the update mechanism changed. At one point each group got GZ Files which were later imported. Now all the GZ's go to a common folder.

OK. Are the release notes (not version history) for the different versions still available somewhere?

The release notes are bundled with each release on the Newsbin Archives page. You'd have to install each release in order to get to the release notes though. As long as you don't launch Newsbin, the only thing that really changes on upgrade are the executables. The data files don't get touched unless you launch Newsbin. If you take this route, be sure to de-select the "Launch Newsbin" checkbox on the last page of the installation and select the "View Release Notes" checkbox.