I've had a 2 inch SP101 in .38 Special ever since they came out and Crimson Trace laser grips on it. I carry the Federal 147-gr. HydraShok +P+ LE loads in it and have shot this gun ALOT with +P equivalent handloads for practice. The SP101 is one of the most sturdy compact .38s out there. In my experience the S&W Model 10 firing +P service loads requires adjustment by a factory-trained armorer every 2000 rounds to avoid problems with excessive cylinder end play from frame stretch. You can stretch the crane on a K- or J-frame twice before cylinder gap opens to exceed the maximum tolerance of 0.008." When you get to that point the gun needs to either have the barrel set back and or have a new cylinder fitted. When I worked at Ruger on the SP101 its design objective was to stand firing 5000 rounds of U.S. Treasury Q4070 110-gr. +P+ ammunition without cleaning, only "dunking" the hot gun in a bucket of water to cool it off, no malfunctions, repairs or parts replacements beyond the user level. That objective was met fully.
Having a .38 Special chambered cylinder is more accurate when firing soft lead or lightweight jacketed bullets in +P loads than when firing the same .38 Special ammo in the longer chambers of a .357 cylinder. I had a .357 SP101 for a while but sold it because it was less accurate with all ammos than my .38 and firing magnum ammunition in the 2-inch barrel had excessive muzzle flash which was detracting. Magnums will perform better in a 3 inch barrel, but I don't miss the ability to fire .357 ammo. The Federal 147-gr. HydraShok +P+ shoots to the sights, has lower muzzle flash than magnum ammo, will stay on my business card firing rapid DA at 7 yards, prints 3 inches or less off sandbags at 25 yards and gets 920 f.p.s. out of my 2 inch barrel. Works for me.