Here's my honest opinion. I have a lot of Glock clones, 8 of them to be precise. I bought Magpul mags to feed them knowing from AR15 experience that Magpul was a good brand.
The Magpul magazines that I bought for my Glock clone pistols are GOOD, meaning they function as they should, but they don't drop as free as a Glock magazine. Most of my mags are Magpul but I have a few Glock. (43x)
Let me explain, I have...some...OEM Glock magazines along with my Magpul magazines. The OEM Glock magazines drop free better than the Magpul magazines. When you hit the mag release, the Glock magazines will DROP. Most of my Magul will not drop without a little help of a tug. Now remember, this is with SCT framed clones. 8 of my Glocks are SCT cloned Glocks. The one Glock that is OEM will drop Magpul mags with no problem.
My AR15 clones will drop all Magpul, Troy and genuine G.I. mags of which most are Anderson lowers. I hope this helps everyone.