Personally, I've avoided relying on unicode/charset semantics with regular expressions. Most of the input I deal with is either Latin-1 or some other "near IBM-ASCII" single byte encoding, and so is my source code. I've made my regular expressions lenient in the sense that I use dots where I expect umlauts.

Of course, if I were more strict about the encodings of my input data, or Perl were more smart about guessing the encoding of my input data (which is hard without carrying a dictionary of likenesses), I could write my source code and my regular expressions in unicode, and then it would be cool if \w would use the unicode semantics.

I have no opinion on \d, as German has only 0-9 as digits anyway, and my input data also.