Hi Jan,

I am sorry, if I understand you correctly, you're not happy with SH404SEF since it changes your site's url structure. In my opinion, SH404SEF can be a good extension to peoples who want to customize their urls. As my suggestion, if you find SH404SEF good, then you can keep using it.

About the Xmap, I suggest to you to keep it disable first, as you setting up your SH404SEF. After you have finished setting up the url, then you can enable it back. So that, the invalid url will not be indexed together in Xmap.

Hope this can help.