I don't know, since I have
never used redirections. I try to plan ahead so I don't need them. For a link collector like me redirections are sometimes bad, since the redirection may end up on a site with different content. That is why automatic link checking tools
Find broken links on your site with Xenu's Link Sleuth (TM) is only a first step in the continual quality control of your links. I am alone, so mine are not good enough.
I love perma links like those we now have at WPW:
Example:
kbleivik's bookmarks on del.icio.us
If these links change, It will be bad for me.