Even though you won't get the 1 pound pull with almost 0 pre-travel but with the Apex AET Polytrigger for the SD and the spring kit you can at least expect a trigger pull of around 6lbs and 0 over-travel. The pre-travel is reduced too. Some people here put the Aluminum trigger for the M&P series in the SD and say it works just fine but Apex did not recommend that - they released the the poly AET for the SD Series for a reason.
You might want to check this thread. They discussed the topic M&P trigger in an SD around post #35/#36
SD Triggers And Mag Extensions Coming Soon From Apex
My personal experience with the Poly SD Trigger and Spring Kit:
Reduced pull to slightly above 6 lbs. and no over-travel at all. Pre-travel is reduced too but I didn't measured it. But it definitely improved the trigger performance and with that my accuracy. I can highly recommend this mod for the SD.