YES, keep those 301 redirects there forever! Why not? Getting rid of them costs traffic and loyalty.

As someone who owns/edits a directory of Websites (with over 9,000 unique links to job search resources), I get very annoyed with people who change their sites without doing permanent redirects.

Please notice that you have other sources of traffic and visitors in addition to search engines:

What about all those bookmarks/favorites set by previous visitors?

What about those e-mailed URL's to check out this great site?

What about my PR 7 link to your site? Plus, all the other links to your site?

People keep trying to buy my "high value links" (NOT for sale). Yet, EVERY month, several hundred of the sites that I GIVE them to, throw them away by changing the URL of the page I link to. ARRGH!

Yes, I run a linkrot checker (LinkAlarm - highly recommended!) every week, and, yes, LinkAlarm indicates which are permanent redirects. And we update those links, but they are less urgent maintenance issues than the newly dead-ended links, and that is greatly appreciated.

BTW, the sites that can figure out how to map from the old pages specifically to the appropriate new pages are greatly appreciated because they are nicer to their visitors AND have made my research into the new URLs much easier.

Dumping everyone onto the new home page is better than a 404, but not by much.

End of rant.