An important aspect of this is also that when a fancy url like this is enabled, it should also be changed in all places where the url is used within the package. E.g. after you created the possibility to say /forum/12345 you should use /forum-view?forum_id=12345 as seldom as possible (from within the package and other places of the toolkit) for consistency. Important among other reasons to not disturb the browser feature to display already visited links in a different colour.
Malte, the /o/12345 stuff is useful for building lists of objects of mixed type, where the computation of the url should be delayed, but it should in my opinion not be used for package internal links, because it results in an unnecessary http (external) redirect.
