Saying hanging has a lethality rate of 89.5 % is very strange to me. This number can only be derived from a set of attempts, counting the amount of attempts that lead to death. It goes without saying that some attempts would be less "sophisticated" than others. In my mind, hanging is pretty much a foolproof method provided the ligature and fixation point are strong enough and that no one will find you during the following 30 minutes or hour. A shooting is much more difficult to get right and if you don't you will hurt yourself considerably and fail because of that. The same is true for cyanide or any other lethal substance. Jumping is similar to hanging. With both methods you can easily 'over-dimension' it as to make it near fool-proof.
And as already noted, an active heartbeat doesn't necessarily mean there is pain. From the same (to me, very credible) web page: "Consciousness can be lost in as little as 8-10 seconds or persist for as much as a minute."