First, if you do it right, hanging almost never goes wrong.
Per this metanalysis of 34 studies, among hanging cases (both partial and full) that result in death or hospitalization, there is an 85% case fatality rate - second in lethality only to firearms. If among those cases you ignore cases where the person was found within half an hour, the fatality rate jumps to pretty damn near 100%. And this corresponds to the anecdotal accounts of hanging that I've seen on sasu, too.
Second, there are studies that indicate that the risk of long-term injury after hanging is overstated. Per a study of hanging patients in France and Belgium who survived to hospital discharge, 96% left the hospital either without neurological deficit or with minor neurological deficit that did not interfere with daily functioning or work. A much smaller UK study found that 82% of hanging patients who survived to hospital discharge left the hospital with favorable neurological outcomes. As for physical injuries, one study of 71 hanging patients found only four patients suffered cervical spine injury, three patients suffered arterial injuries and two had laryngotracheal injuries. A similar, large, multicenter study also found vascular or laryngotracheal injuries to have occurred in only 6% of near-hanged patients. (
Source for all these studies here.)
Now, I've heard anecdotal reports that the risk of long-term injury may be greater than those studies suggest, so your mileage may vary on the above studies. But, like, say the odds of successful hanging if you do it right is 90%, and the risk of long-term injury if you fail is 50% - much higher than studies suggest - then that's a 95% chance of death or no injury, and a 5% of long-term injury. And as you mention above, in that 5% chance, there's still a chance that you can attempt again or qualify for MAID. Those seem like pretty good odds to me. But at the end of the day, it's entirely up to you.
Wishing you well :3