I have a shield and yes the Apex Tactical trigger is worth every penny you pay for it. I have actually swapped all 3 of my M&P guns to some version of their trigger. For the shield I use the duty carry kit with the replacement trigger. I think it increased the pull slightly, but it is a lot smoother and shorter. I did not pull it with a scale before and after. Comparing it to another stock one a friend has I think it is slightly higher. For my full size ones, I put the forward set sear and trigger kit in them. The Apex triggers are like Glock with the little safety tab in the middle of the trigger instead of the bottom portion being hinged in the stock M&P. Mine all have the aluminum trigger, but I think the polymer trigger kit would be about the same.
Of course this advice is coming from a guy that cannot leave anything he owns alone. I like taking things apart and putting them back together. Doesn't really matter what it is.