I recently added the Sokek Solutions AT-X/C folding thumb rest. I love the idea behind it but with the stock AI grip I am not a fan as there's very little room between the hinge and your thumb. I currently have an MDT Vertical Elite Grip en route, I am hoping that the vertical grip will allow for more room for your thumb between the hinge and the rest or at least a better angle. If not I'll remove it and go back to resting my thumb on the folding stock hardware.