MarkOly - 5:22 am on Jul 2, 2013 (gmt 0)
The reason you feed both good and bad URLs to Xenu in the text file list is to test that the site returns the correct response for both correct and incorrect requests, for wanted and unwanted requests. You add a selection of page names that don't exist, incorrect extensions, unwanted or unnecessary parameters, and so on. Some of my test files have thousands of URLs and can quickly verify that I haven't introduced problems when altering the site configuration.
That sounds like a great idea. You can have different text files for different categories of error. Beats entering URLs one at a time. The only thing I see that could be improved on would be to report the actual response code in the list view, rather than "ok" or "not found". The 301 redirects and the 200's all report as "ok". You can view the redirects in the html report though.