I discovered exactly the same thing, nowhere nearly as scary as it first appeared.
in reply to Re^3: Changing Perl compile-time configuration settings
in thread Changing Perl compile-time configuration settings
So I've implemented the auto-detecting version of Config_heavy.pl as well, and added it to the repository.
I've noticed the unix paths as well, but I'm unsure what the hell the implications of that are...
Should I go through the makefile before I compile Perl and strip all those out? I dunno yet...