As far as I've heard and read, the Shield's trigger is the same as it's always been and it has always felt better than the other M&P triggers. I've always hated the 'standard' factory M&P triggers, but the Shield's trigger impressed me enough to go ahead and buy it. That was Three Years ago.

Supposedly, the OTHER M&Ps started incorporating parts of the Shield's trigger system a year or two ago.

Find someplace that has a shield to rent, or someone who has a Shield you could try and see if you like it. In the store, a brand new Shield's trigger may feel a bit gritty, but a quick polish of some of the parts (or shooting a few Hundred rounds) will smooth them out.