ctcentralinfo:
So what issues where you having with this mod.
There are so many scenarios causing issues that I really don't have time to go into all but here are a few...
Search Engines are confused when generating url for index when this mod is activated. MSN and Shopwiki are the ones affected the most, they keep adding all sort of garbage to the url like adding extra // in the wrong place and then when the url is clicked from index it returns 404. This behavior also changes depending on whether you're using .html or / or blank extension or not. Each one creates a different misformed url issue.
The setting of .html also breaks with Paypal Express unless you have seo url enabled for ssl (which I really don't want).
Some crawler/search engine are actually confused when no extension is indicated because they tried to look for what would be a default file type so when reading a url that ends with no extension (in this case) it causes other 404 issues. Obviously, there are a lot of site when this methods works just fine so it could be a configuration issue with my server or other things but there are issues nonetheless.
To be fair, this mod was released and we were all advised not to use this in production environment but of course I didn't listen to that. I have successfully uninstalled it and things are working fine and urls are not creating problems. For now I will go spend my time on making money instead of chasing bugs (if and when there is a production release of this mod, I might take a chance again).
One last piece of advice, to a naked eyes this thing looks like it's working flawlessly but you have to dig deep to find some of the issues. If you have user tracking installed, view the session for some of the search engines/crawler and you will see some of the stuff that may not be easily obvious. If you error log is set to capture the right logging to reveal all the different error messages, check it regularly. If you have awstats, run the report and take a look at the http error code, click on the 404 to see what's happening and try to dissect various things that are obvious.