Regardless of how superior/inferior a particular variant of a missile might be, if the aircraft was not equipped to fire that missile it should not be included in the module. There is more to firing a missile other than if it fits on a pylon or not. Avionics and equipment need to be compatible as well, and while I understand the appeal of balanced game play I have to point out that what we get are simulations of aircraft, their capabilities, and equipment and sometimes that means the playing field is uneven and unbalanced. If the missile was ever used by the Harrier then by all means include it. if it wasn't, then leave it out.