If you weigh the pros and cons of the mag, its up to you to decide. I have a buddy that uses them and swears by them. I asked him what makes them great? He said that they feed ammo well, and they insert easily into the magwell....
In my head, I thought to myself...oem glock mags do just that. But for a fraction of the cost. He even had a mag get untuned and had to send it back to mbx to get it retuned... Never had to do that with oem.
Also my opinion, the top shooters dont use them because the oem ones just work. If I see Josh Froelich, Max L, and Zach S start using them without any sponsorship, Im all for it. But these champs found a way to fine tune their poly mags. Not worth it...Just my 2 cents.
I think I would rather buy $200 worth of ammo or a backup bolt.