If it isn't unfired, shooting it some more is not going to affect the condition, value or historical significance. Obviously, more than the usual care to preserve condition is in order, but the gun was meant to be shot, so doing so is an appropriate thing for even one with the "caretaker philosophy" to do. JMHO, YMMV.

As for the 4- vs 5-screw versions Candyman, the 4-screw was made for a shorter period of time, and I would expect it to be at least somewhat more rare. Regardless, that gun was made when both quality and pride of workmanship were givens at S&W, and you have a fine example there. Enjoy it (in spite of all of our jealousy here! ) Congratulations!

Froggie