If you look at an exploded view of the polymer part you will discover that it's mostly the trigger guard, and not a whole much more. Like other Ruger D.A. revolvers the trigger and cylinder stop parts are housed in the trigger guard. But there isn't a whole lot there which can affect felt recoil. On polymer pistols the whole lower frame, including the magazine well, is polymer, and that’s a whole different situation.
But while the polymer trigger module on the LCR doesn't have much to do with felt recoil, the new stocks do. Both the shape and material (and the fact they are hollow in the right places) will likely make a positive difference. However, if they choose to do so, both Smith & Wesson and Taurus can offer similar stocks on their revolvers. But I predict they'll wait and see how the Ruger goes over with the buying public. Not everyone is going to be turned on by the "plastic trigger guard," nor the suggested retail price. If anything, it's the improved(?) trigger pull that will sell the Ruger, but again - both S&W and Taurus can make changes, and they're revolvers have a more conventional look that shouldn't be underestimated.