My opinion: The Rapier would be a nice ship if it cost half the price. At more than million credits the Rapier is just barley better than Ligthning, and is plagued with the same problems. Lack of shields and a low cargo hold makes this ship neither a good fighter nor a good merchant ship. The Rear Laser Turret, the unsellable upgrade that fills the turret spot only fires across 90° spectrum from the rear — not too useful. However the Rapier makes a great escort fighter. Since cargo room doesn't matter much to an escort, its lack of it isn't a problem; and those heavy rockets can pack qutie a wallop, as do the guided torpedos.
Computer controled: The Rapier follows a similar flight plan to that of a Lighting: suicide bomber. Avoide the heavy rockets and you'll be fine. The computer rarely has the Rapier fire torpedos at you so hitting the enemy Rapier with a few missles or torpedos shouldn't be a problem. But try to aviod firing torpedos at it, they're too slow for a quick ship like a Rapier.