Since S&W considered the half cock notch a "safety" feature, I would strongly discourage trying to mess with it. Liability issues.
The 3rd Gen guns are definately refinements of the 2nd gen guns. The TSW is a further refinement. Expecting the 469 to act like the TSW is unrealistic. If the 469 has hot been fired much, shoot or dry fire the heck out of it, then detail clean and lube it. It will get better.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball