Pointing to a specific perl binary makes sense if distributing a script to a system where you may not have control over the PATH.

Or if you want to make sure it uses a specific (non system) perl install that has modules installed that are not available in general distributions or have libraries linked that are specific to the script or …

Personally I always use #!/pro/bin/perl, which is where I have my production perl installed. If I do not need anything specific, and system-perl will do (which is seldom the case), I make /pro/bin/perl a symlink to the required perl. TIMTOWTDI