Well, to keep your current urls it would be the simple mod, you could just play with the static part in phpbb_seo_class.php as explained in the install to for example use about instead of topic.
But SEO wise, I'd encourage you to consider changing urls, feature such as the virtual folder option are great in mixed mode :
- Code: Select all
forum-url/topicxx.html VS topicxx.html
And you do not risk anything as long as redirects are in place (which is decently easy), many forum already did such migration without an loss in SERPs and SE referrals.
Of course, the PR of the new urls would be 0 at first, but this will only last until next update and again is not related to what really matters : SERPs, indexing and referrals