Yes, installing a mainspring from a D model will make it lighter and smoother. I've done it to 2 of my guns and no light strikes yet.
Gun Control-gun con·trol n. definition 1. The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker received that fatal bullet wound. 2. The ability to hit what you are aiming at.