From my perspective, either one requires some education of CPAN authors. Thusly educated, the author can make their own decision.

In my case, I already do 1. Have since nearly the beginning since I've always had to deal with Windows and Unix at the same time, so I've just enforced a coding standard that said "always use File::Spec to create file paths." Hopefully if they ever need to support Mac or something else, it just works. (Then again, since I'm not on that team anymore, it's not entirely my concern anyway ;->)