Robo,Of course one should follow the manufacturers recomendations on ammo. Metalurgy and heat treatment on this series of revolvers is better than the previous generation and not a good as the next generation. The knowledge of the maker evolves with time.
To make a blanket statement tht you can shoot +P in your revolver, sight unseen is (IMHO) somewhat irresponsible.
The main problem you will experience from a steady diet of +P ammo is a condition called "End Shake, Cylinder". This is caused by the peening and shortening of the crane (the part the cylinder spins on and that swings open to expose the cylinder for loading/unloading). Pre '77 cranes were prone to this. It is a condition that is fairly easily corrected and is much more slow to reappear after fixed with shims.
I have a 1955 45 made before it was given a model number and expect it has never had +P ammo shot though it. I know for the 15+ years I've owned the pistol it hasn't. All the same it has end shake and considering it's 54 years old I'm not surprised, overall it's a great pistol and truly want to correct this issue. The vid was pretty good but lacked the detail about the gap, it showed how to measure but didn't explain the measurement in relation to size of spacer required.Here is a vidoe in you tube to show you how to fix endshake.It would probably take you about 30 years of shooting plusp ammo to need to do this but here is a video that shows how easy it is to fix it.
YouTube - Gunsmith - Fix excessive cylinder endshake in S&W revolver