A few years ago I bought a 457 that came with seven magazines. Two of them were unmarked aftermarket magazines. I assume that they were Pro Mag. They would not allow the 457 to fire double action because of a very minor out difference in how the magazine interacted with the magazine safety. That caused me a bit of consternation until i determined that the magazines, not the gun, were the problem.
My 3914NL came with two aftermarket magazines, which functioned fine. Despite that, i got rid of them along with the 457 mags. Maybe okay for range use, but why bother?
I've spent the past few years acquiring magazines for my 3913/14 guns. I never passed up an opportunity to buy them if the price was right. I also bought base plates, springs, and followers. Probably more than I'll ever use, but better to have them.
Same thing with the CS9/non rail 3913TSW magazines. I got some good deals on those, mostly because the seller didn't know what he had. His loss, my gain. I even called S&W and got those wedge shaped base plates.
I've bought Mec Gar and S&w 59xx magazines and there is absolutely no difference other than the markings. Unlike Pro Mag and other aftermarket magazines everything interchanges. I'm convinced that Mec Gar was the OEM for 59xx magazines, but I've never seen any other S&W magazines offered by them.
Mec Gar sells a number of different magazines for various brands as well.
I don't if this shortage is temporary or permanent, but I'm taking no chances.
Well, the last thing I want is magazines that aren't totally reliable whether for carry/protection or not.

The ProMags sure are cheap and plentiful (dozens of them in 3913/3953/908 at the last show) but I'll pass if they are not up to the highest standards of reliability possible.