I don't have a Shield, but I do have an M&P9C, 40C, and 40FS. The Compacts are
almost the same gun as the equivalent Shield.
I also had a PPS40....
I swapped the PPS40 for a 40C (or maybe the 9C - I don't remember

).... The PPS40 was a fine gun, but the very narrow trigger was such that my pudgy fingers wrapped around it, causing a pinch with each shot. (My KelTec P3AT does exactly the same thing, but it's a "carry often, shoot rarely" gun anyway....)
Cutting down the triggers (less trigger to wrap around) helped a little, but not much.
The somewhat heavy recoil of the PPS40 with the narrow grip width was punishing, too, but tolerable for a 1911 guy. Using a cheap shooting glove on the range was all that it took....
S&W uses a fairly wide trigger on the M&P's, and it appears that the Shield is using essentially the same design. The M&Ps I have are quite comfortable to shoot (including the 40C). A Shield 40 should be a bit rough, but certainly not as bad as the PPS trigger, at least....
If you find the trigger
action v.s. the pinch effect to be gritty, stiff, etc., just shooting it for a while should clean most of it up. Slathering Gunslick all over the action parts would probably help, too. If you don't mind spending a few bucks, Apex has a cleanup kit for the Shield (similar to the DCAEK kit for the larger guns) that will take most of the problems out, and a new polymer trigger (they also have a metal one, but it's very expensive) that's a little better than stock.
I have the DCAEK on my M&P's, with
excellent results. I have no problem with the stock triggers, even with the hinged foolishness, so I haven't changed any of those. YMMV thing....
I'm big enough to conceal a full sized 1911 (or, my preference, an "Officer's" sized 1911), so the double-stack M&P Compacts are no problem - I really don't need the thinner model most of the time. But that's also a YMMV. My very petite daughter (at 27!) can't conceal anything much bigger than my P3AT in summer clothes, even if she dresses around it, but might have a chance with the Shield v.s. the 9C.
I tried to swap the 9C for a Shield 40 a while back, but got no takers. Someday, maybe....
Regards,