I got a great deal on a Performance Center M&P40 Shield back in January, LNiB for only $350!
It was new old stock which left the factory in 2017 and apparently just sat on a shelf somewhere collecting dust until it went on Clearance for $350 and I bought it. As near as I can figure, it didn't sell because it it's .40cal, which we all know totally died the instant that the FBI decided that they were switching back to 9mm.
On the subject of slimline double stacks vs single stacks, I'll say this much... Folks are quick to call out that the Shield PLUS weighs about the same as an ordinary M&P9 Shield and holds more rounds, yet apparently forget that those extra rounds in the magazine add to the overall weight of the gun when fully loaded, so unless someone is already carrying a few extra magazines to equal the amount of ammo that the PLUS offers in the first place, then they've added weight to their carry load by upgrading to a Shield PLUS.
Personally, I'm still carrying the M&P40 Shield 1.0, and even if S&W comes out with an M&P40 Shield PLUS, I'm still going to carry the Shield 1.0 because it's lighter, and that's more important to me than capacity when it comes to Summer carry.
I know that a mere 7 rounds won't provide me with enough ammo to use in suppressive fire once I've inevitably been accosted by the dreaded Crackerjack Boys at the local drugstore, nor would 7 rounds be enough to overcome the superhuman fortitude they've somehow obtained through the medical miracles which occur as the end result of otherwise crippling chemical dependency on a potent mixture of narcotics and caramel corn, but somehow I've managed to go my whole life without encountering any such illusive villains, so I'll take my chances.