I have a great little 469 and a recently acquired 4513TSW. Both are double action for the first shot and single action thereafter. The 469 has a combination safety/decocker lever which stays down after dropping the hammer, while the 4513's lever drops the hammer and returns to the fire position. The 469 also has a half-cock notch, and the 4513 does not. The other difference is what I'm mainly concerned about: In double action mode, the 469's trigger "stacks" (gets heavier) just before releasing the hammer, while the 4513's trigger pull is smooth all the way through.
I would like the 469 to have the same smooth trigger pull. Is this a matter of tuning the trigger, or just a fundamental difference between the 2nd and 3rd generation pistols? Also, I see no benefit in having a half-cock "safety" notch in a DA pistol with a bobbed hammer. Apparently S&W agrees, since it's missing on the later 3rd generation gun. I'm thinking seriously about removing it if I do any trigger work.