I used McCormick Power 8s for many years, with no issues. I had to occasionally replace the springs in the less-expensive Shooting Stars.
My preferred mag today is the Check-mate extended-tube "competition" mag.
My IDPA club did some testing on the prototypes, three or four years ago, and Check-Mate was extremely responsive in addressing the issues we identified. I'm sure we weren't the only ones evaluating them, but we would often have revised mags in hand within a month of communicating a problem, and they continued to improve the tubes, springs, basepads, etc., based on feedback from shooters.
Top notch stuff.