Something along this line is being discussed for perl6 but as you have discovered from other posts most perl types ho-hum it. =) It has the same potential issue as prototypes where the first scalar might cause an array to be cast into scalar form:

sub popntuple1 ($one, @two) {
  return $one, \@two;
}
sub popntuple2 () {
  my ($one, @two) = @_;
  return $one, \@two)
}

my @a = ( 1, 2, 3, 4);
my @b = ( 6, 7, 8, 9);

($p, $t) = popntuple1(@a,@b);
($pp, $tt)=popntuple2(@a,@b);
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If the scalar causes a cast, you get 4, (6,7,8,9) otherwise you get 1, (2,3,4,6,7,8,9). And if it doesn't cast, what did it save you?

--
$you = new YOU;
honk() if $you->love(perl)