I just started running the Recover Tactical MG9. It comes on and off without tools, so I can use it with my other glock mag PCCs.
There are a couple drawbacks to this model. Since it doesn't use tools to "clamp" it onto the rail, it moves a bit forward and backwards. Very minor, but it does. I may 3d print an adapter/spacer to eliminate the movement.
The mag release/latch is just a tensioned section of plastic and while you're not likely to be doing tons of mag swaps with it, I imagine it could have trouble holding heavy 32 round mags, years down the road, especially if you hold onto the mag. You just pull, firmly, to remove the mag. It may last forever, but there is a potential for wear to affect holding power.
It is built well, looks good and is comfortable to use as a forward grip, if needed. You can remove the whole thing and put it on another rifle, in the time it takes to eject a mag. Recover Tactical has great customer service too and if there ever is a problem, they will take care of you.