I have one that I have been running with my daily wear uniform. I use it for what
@runningwolf uses it for; active shooter, SHTF rig. I also use it at the range when teaching academy and other firearms classes.
I chose the MOLLE magnetic placard so that I could have the most options to set it up to my liking. Initially I had it set up with two generic AR15 rifle pouches and quickly became dissatisfied with it. For it to be a serious setup it needed more function than to hold two rifle magazines. I have since changed it out to an Esstac pouch (single rifle, two pistol ) and a small med pouch.
The magnets inside are strong and in my opinion could be a tad stronger. In personal testing the fully loaded placard stays tight during physical activities (running, jumping, climbing). It is possible for the placard to shift if you bump into things. During ground fighting training the placard came off every time.
I like the metal plate insert it comes with. My agency is issued Point Blank vests and the insert fits tightly and doesn't shift. Plus the insert is tall and runs from the bottom of the vest panel to almost three inches below the top of the front vest panel. What this translates into is that when responding quickly to an incident I don't have to be exact in the placement of the placard. I can always adjust it later if I have to. This also gives the placard plenty of space to be moved if need be depending on what I'm doing (standing, sitting, prone, etc).
@Oak City Tactics I will agree 100% that the weight of the placard is negligible. You will however notice the plate because it is on the outside of the armor panel next to the carrier. The vest is just as concealable as before. I am curious however if the insert provides any stab protection but not curious enough to test out my insert.