Well, it depends...
First of all, Buffers? Never. Especially not for any arm intended for serious purpose. A buffer takes up space. Nearly an eighth of an inch or thereabouts and will short stroke your slide an equal amount which may cause feed and/or ejection faults.
Now about recoil springs...
First of all, realize that extra power springs throw the slide back into battery with more force & speed than the factory rated spring does. This means you'll be beating the snot out of the mating slide/barrel locking lugs, stop pin and camming lug.
Spring your guns according to how they behave with the loads your shooting. Pay close attention to the recoil impulse. Excessive muzzle flip & sharp rap in the hand would lead me to install a firmer spring. Also observe closely how & where your brass ejects. Violent ejection launching your brass into the neighboring county would indicate a weak spring which goes hand in hand with the aforementioned excessive muzzle flip & felt recoil. Conversely if the brass is trickling out and landing at your feet, there's too much spring in the gun.
I like my empties to land about 4-6 feet away at around 4 o'clock and spring my guns accordingly for the loads I shoot.
Do not use extra power recoil springs as prophylaxis against possible battering. Extra power springs and reduced power for that matter are intended for addressing issued with function & reliability applied to certain loads. ie. light spring for target loads, standard weight for standard loads, +p or +p+ loads may merit an extra power spring.
Newly acquired guns with unknown history/round count automatically get a fresh S&W factory weight spring. Then based on some range time observing how the gun behaves, I'll determine whether any change in spring rate is merited.
A fresh recoil spring is cheap insurance against undue or premature wear on a semi. I got bags of springs and change mine regularly as conditions or round count indicate.
One more thing...
Don't discount the mainspring or hammer spring. When firing this spring does much more to delay unlocking and throttle initial slide velocity than the recoil spring does. Recoil springs would be more appropriately named return to battery spring as that is their primary job, throwing the slide forward into battery with a fresh round. Mainsprings can be tuned as well and may be had in different weights.
In the end, keep good spring in your guns. And stop worrying about possible battering. Start with the factory S&W springs specified for your gun. Replace then periodically. The factory standard is every 5years or 5000 rounds as I recall. I tend to be a bit more liberal with replacing my springs especially in my carry guns. Cheap insurance to make sure they work when needed and last a good looong time.
Cheers
Bill