Shareaza

I would like to use this regex to ban all search results with eight or more 4 character words: (\w{4,}\W+){8,}

It is valid Perl syntax, but I am not sure it is working. I know Boost uses Perl regexes by default, but does Shareaza do so aswell?

By default its posix-compatible.
You can use RegExp.exe utility to play with Shareaza regular expressions (it uses same source files as shareaza itself).