Hi,
DocumentUrlPath property in lowercase doesn't ensure that you won't be able to have a link with URL in uppercase (or undesired case). The mentioned solution in global.asax is suitable, however you're right that it's not a very nice solution.
Although this forum is for 4.x versions, I'd like to point to the new version (5.x) feature where you can specify upper/lowercase behavior of the URLs.
More on this can be found in article about
URL format and configuration in our DevGuide.
The new feature is represented by setting "Redirect invalid case URLs to their correct versions".
Regards,
Zdenek C.