There is one worry, though - that of split Pr if you don;t redirect users to the form you are promoting.
In other words,
http://www.website.com
http://website.com
If someone comes to your site via the form that you are *not* using, then relative URLs *without* a redirect to the form you are using may result in your natural backlinks being messed up.
Ideally, you should use a redirect for the www or without www form, when using relative URLs. Using absolute URLs removes the problem for internal links.