There are two places to configure drutex, one at
admin/settings/filters/3/configure (the number 3 may be different on your system)
the other at
admin/settings/drutex

I'm not sure why, but it's rather puzzling.
The second is a subset of the first. But even in the fields that are present
at both pages, there is a difference. The one that prompted me to write this:
on admin/settings/drutex you have less choice in the conversion method
(just three as opposed to six in the other page).

Workaround is not to use the page admin/settings/drutex, but I suppose
it should be at least mentioned somewhere ..., preferably not happening.
Or am I missing something?