I can provide some real-world information on Metalform magazines.
Back in 1999, I ordered a hundred of'em...evenly split between stainless and carbon. All of them are 7 round with the standard flat follower with the speed bump...as per original design.
At the same time, I ordered 50 Wolff 11-pound springs for the carbon mags. The stainless versions were available with the Wolff spring upgrade for an extra buck a copy.
I kept 72 of the magazines for my own use, plus a couple spares in each version just for a backup...and I've used'em hard. At one time, I carried all of them to the range an average of twice a week...preloaded...and emptied them all. I wasn't gentle with them. I slammed'em home and let'em bounce on the ground when they were jettisoned. I take them apart for thorough cleaning once a year.
Last month, the welds gave up on the floorplate on one magazine. One magazine failed in 11 years. I salvaged the follower and spring.
In 11 years of hard use, none of the Wolff springs have failed. Not one. None of the followers have failed. None of the magazine tubes have dented or sprung. They're starting to looka little rough, but they're still on the job.
I'e never had a feed failure in any of my guns unless it was due to a bad round of ammunition. Shooting my own cast bullets almost exclusively...once in every great while, I run into a bad one that doesn't want to chamber...but those are few and far between.
None of the magazines has failed to lock the slide on empty except in the case of a broken slidestop lug...and that's happened twice in two Colts...once per gun...that have seen hard use since 1991 and 1992 respectively. Not the fault of the magazines.
Would I recommend Metalform 7-round magazines? Absolutely. As far as the one that failed...If I send it back, they'll send me another one...but I probably won't bother to do it.
Disclaimer:
I have no vested interest in The Metalform Company, nor do they send me free goodies for my endorsement of their products. I'm a customer like any other. No more and no less.