Let's take this one question at a time. The captive recoil spring combo helps absorb some of the energy thus reducing recoil somewhat and the battering of parts of the gun. This may also assure reliability of the gun in theory.
Manual safeties have several functions and reasons to exist. Even with a heavy DA trigger pull there are certain situations that could cause the trigger to be pulled inadvertantly discharging the firearm. On the draw,especially under duress, people are known to put the finger on the trigger before the fire arm is out in front of the person and pointed at the target or in a safe direction.An object could get caught in the trigger guard with out being noticed and set off the trigger, firing the gun.Sounds fantastic, but it happens frequently. It will not be seen in print or discussed in most instances, embarassing as it is.
When reholstering, putting the gun on safe and then sticking the gun back in also stops negligent discharges. The gun is cocked and light pressure will set the gun off again. Reholstering normally or under stress has caused many an accident with serious injury or death. Trigger fingers are in the trigger guard as the gun goes into the holster and BOOM results. This happens to novices and veterans alike. Then there is the protection from an assailant who grabs your gun to use against you. Happens frequently to police and citizens frequently despite what one might think.
If the pistol is "on safe" and the attacker gets the gun, he has to figure out which button or lever makes the gun"off safe" to function. This gives a victim time to go to plan B and a few seconds to act decisively. This allows one to get the gun back, run, or draw a backup weapon and neutralize the problem, or gain supremacy over the situation again. Depends on the circumstances of the situation.
As for the +P problem, since the catalog says go with +P loads then it is safe as long as certain things are considered. +P is not needed for most defense situations regardless what "conventional wisdom" says. Most standard pressure loads will get the job done with out the added recoil ,muzzle flash, and power regardless of caliber. From short barrels the gain of +P is not that great in power or velocity. The powder expends most of its energy outside the abbreviated barrel burning up. Or not even burning completely. Staying with standard pressure loads within SAAMI specs is a good idea all the way round. The higher pressure loads mean accelerated wear ,tear, and battering of gun parts and frame.
Some minor use of +P for practice purposes and to stay current are reasons to use it. Then carry +P in your firearm in confidence. Especially if the pistol or revolver has a service length barrel. If the manual states a certain bullet weight and velocity for that caliber, then do not go beyond those boundries set in the manual. Otherwise unsafe conditons can cause serious harm to the shooter and firearm, including leading to death. Over pressure ammo is never a good idea. SAAMI sets the rules and the ammo companies and gun makers stick to those rules. +P+ is usually never a good idea. Unless the gun manufacturer gives it's blessing. They know the guns limits. Most guns are strong enough to take some abuse, but why even go over the limits? Severe injury or death are not worth the supposed gain in performance.
THe .38 Super is a neat cartridge, but the theoretical advantage over the 9mm. and .45ACP just are not there unless one reloads for this cartridge. Modern loadings have down graded the velocity due to the older guns out there in this caliber and due to ammo liability. One has to be safe even when reloading. There is the tendency to hotrod this cartridge to dangerous levels. This has happened somewhat in IPSC. There are +P loadings for this cartridge, but are hard to find and the expense can be prohibitive. If one competes in IPSC then there may be a need to have such caliber and gun. Or just because one wants to shoot one. Again expense can take a bite out of the pocket book.
The .38 Super was designed to penetrate the car bodies and criminal's body armor of the times during the 1930's. Other calibers were unable to do this under most circumstances. The last answer to the last question I will have to leave to others. Hope this helps. In the last 5 to 10 years Taurus engineered their guns to take +P ammo use. Use it sparingly and your gun will last longer. Check the pressure levels of each +P or +P+ ammo before using to make sure they are within the set limits. If in doubt, don't shoot that particular load.
