Good article!
Personally, I only shoot once, and don't let those that hunt with me shoot more than once, unless the tom is obviously injured on the first shot.
If I miss with the first shot, he wins and I let him walk or run off. And I'm OK with that. Just my personal rules.
Now I do carry 2 more lead 6s in the magazine following my #9 tss initial shot. Those are to dispatch an obviously injured bird (one with his head still up and moving on the ground). Fortunately, that has happen only once since I made the switch to TSS 4 or 5 years ago... one my son shot a little low, the bird rolled, and as we were walking to him, he picked his head up with an obviously unsevered spinal cord. I had him put a 2nd shot of lead 6s into his upright head.
But to me, slinging shot as a followup after a miss is going to result in an injured but unrecoverable bird more often than an ethical kill.