Hmm, you've made me sit up and take note. Right now I have a domke gripper on my M3, and like the strap quite a lot (seems the only one aside from the Leica M strap that is long enough to sling my M around the chest). I like the ability on the strap to slide around my shoulder, when I need to pull the camera up from its position at my side, to my eye, and to that end, have the rubber on the gripper strap turned around the other way so that it does not rub and grip against my clothes.
To that end, velcro is a no-no, but I have long considered stitching the end of the strap onto itself, so it never accidentally releases itself, as to be honest, I do not see this strap coming off my M3 at any point in its life. Also thought about rubbing wax on the the cloth end of the strap, so it does not free itself so easily. Hmm, time to go look for a darning needle and some heavy duty thread here..