FWIW, the drawbar plunger spring (what's called the trigger return spring by Wolff) has to properly tension the drawbar so its tail is lifted up underneath the hammer's DA notches. The drawbar's tail notches must firmly engage the hammer's "pickup" notch, and then the "throw" notch, in order to provide for a full force hammer fall in DA.
Reducing the power of the spring may risk the drawbar tail not being able to firmly and briskly engage the hammer notches. If the drawbar "drops" the hammer prematurely it's called Skips-DA, and the symptom is a light-strike.
I've never known of a factory drawbar plunger spring to wear out. I'd rather have it strong enough to maximize helping keep the drawbar functioning even if the gun becomes dirty or suddenly contaminated (dropped in water, dirt, sand, etc).
I've experimented with reduced power drawbar plunger springs, and have not been able to notice a significant "improvement" in trigger pull. I did, however, experience a Skips-DA condition after a while. (In one gun, and it wasn't worn hammer or drawbar notches, either, as replacing the spring immediately resolved it.)
Notice on the Wolff website that they offer a cautionary warning about their reduced power trigger return (drawbar plunger) springs: WARNING: Springs are for competition use only - NOT for duty use.
It might be prudent to consider substituting the word "defensive" for "duty" in their warning, if you plan to actually depend upon the guns as dedicated defensive weapons. If they're just going to be "range" guns, then any reduction in their ability to function normally may not be as much of a concern.
The reduced power mainsprings are longer than the factory stock springs, but I've been told by the good folks at Wolff that it's because of the way they design and make their springs (coil wire gauge, etc). Also, they don't "close" the ends of their coils, flattening and grinding them, in the same manner as the factory specifies for their mainsprings.
While I've previously used the reduced power mainsprings without any problem, I've gone back to using the stock factory mainsprings. They're heavier than reduced power springs, yes, but they're also intended to help keep powering the hammer to ignite rounds under less-than-optimal conditions that may occur (hard primers, dirty gun, etc).
I've replaced a few factory mainsprings in 3rd gen's that were 20-25+ years old, but that was because they were really nasty in appearance (one looked like it had been "painted" black?!?), or were looking a little corroded. I haven't yet observed a significant shortening in length, or a noticeable reduction in strength, of such older factory springs, though.
My own 3rd gen's, going back to the late 90's and which have been well used on the range, have factory springs in them. My CS45 and original 4513TSW, both produced at the end of the 90's, have their original factory mainsprings (and drawbar plunger springs) in them, although I've used them hard enough to have replaced many recoil springs.
Just my thoughts.
