I had a fairly simple issue to deal with. I wanted to change out my permalink structure from a legacy structure “/%category%/%postname%/” to /%postname%-%post_id%.html.
After looking at a few options available, and testing some out I found Dean Lees Permalink Migration plugin.
The tool worked flawlessly.
There are , of course, other options out there. One is John Godley’s Redirection , personally I found this one to be overkill for my specific need. Also, in reading others impressions there seems to be a distinct amount of processing load placed on the server. But, hey it may be right for you, watch out for the endless redirection errors in IE.