light, lighter, lightest. Although you have the lightest of the J Frame Centennials IMO it was a pendulum swing to an extreme when the PD Series was develoed. Light yes, but if you shoot .357 you will pay the price in felt recoil and possible cylinder issues including crimp jump.
The M&P 340 was a redesign based on moderation and some enhancements.
13.3 ounces by using a more robust stainless steel versus Ti cylinder, which of course could and has been retrofitted to PDs, so not to worry.
Finish, including the superior wearability, stealth and durability of the "DLC".
The big deal is the XS standard Tritium Night Site, and ramp combo providing a quick point and shoot experience superior to the blade or light pipe providing the all the advantages and NS capable. Of course part of this shortcoming can be overcome with CT Grips.
I can't speak to the price but the features/benefits from steel, to alloys of the X42 to the PD and back to to a more conservative approach and additions of some strong features were a step in the right direction in the evolution of the genre to the M&P 340. A Snub yet to be excelled.