Yes these mags have been fully tested and these E-Lander made magazines are of super high quality. If you have seen the E-Lander AR-15 magazines you would understand.
You can't compare these to the KCI mags as it really isn't comparing apples to apples.
In all fairness I have been running the KCI mags without any problems. If you check in the forum there is a thread discussing them and the couple of little suggestions I made on how to tweak them just a little for the best performance. We have sold a couple of thousand of the KCI mags and have only had a handful sent back from people who weren't happy with them.