My M&P 45 also had a rather heavier and stiff trigger right out-of-the-box. When I checked it with my digital gauge I received some cycle averages running around 8.5-9+ lbs. That's still within what we were told was a normal tolerance range of +/- 2 lbs (the .45 has a 7.5lb trigge weight spec, I believe, instead of the 6.5lb spec of the 9/40/357 models). It figured that I'd get one on the heavier end of the range.
Anyway, after the first couple of range sessions (approx 200 rounds per session) I noticed the trigger was a lot smoother and 'felt' somewhat lighter. I didn't notice that it had improved at first because it hadn't been adversely affecting my accuracy from the beginning. I was very pleased and impressed with the inherent accuracy of my M&P 45. I was just focusing on becoming acquainted with the gun, using the basics of good grip, sight alignment/picture and an evenly delivered trigger press.
I no longer reload or use 200gr LSWC .45 loads so I was only interested in how my M&P 45 performed with standard Ball and some assorted JHP's. It fed 3 different types of duty-type JHP's and some small number of Ball loads with monotonous reliability.
I've used my M&P 45 with duty-type JHP's to make some groups as small as 4-5" at 50 yards shooting from a standing unsupported 2-hand position as well as a kneeling position. I suspect the gun is more accurate than that, or it might be in the hands of someone more skilled than myself. I'd imagine some experimentation with different loads might reveal the potential for some better practical accuracy at such long handgun ranges, too.
From the more practical perspective, I've been able to make some reasonably tightly overlapped, ragged hole groups at 15 yards as long as I do my part well enough.
I haven't bothered to check the trigger weight again because it's been doing so well for my needs and expectations.
I actually enjoy shooting my M&P 45 more than my several 1911's.
FWIW, even when the 'new' trigger was still stiff and somewhat 'less than smooth' I was able to experience very good results when practicing with fairly rapid shot strings.
Now, I own, used and shoot a number of different pistol designs, so it's not like I exclusively limit myself to a particular design, make or model. They include single action, traditional double action and some of the various 'double action only' variants being marketed.
Now, my M&P40c does have what feels to be a lighter trigger, but I didn't bother to check it with a gauge since I was only interested in my ability to use it, and not the specific 'trigger weight'. That required checking it on the firing line, not at the bench using a gauge.
But hey, I'm a long time traditional double action revolver shooter, so the 'weight' and 'reset' of most of pistol designs and actions aren't exactly something which keeps me awake at night.
Of course, this doesn't mean I wouldn't mind seeing what a Performance Center machined sear might be like if a M&P 45 Pro Series were released in a compact model.
The trigger weight and break, reminds me of a good 1911.
