Well Shibboleth, I guess the Canadian exchange rate must be improving
Excellent post, but I have a couple of nitpicks:
1.) It’s not the New Testament that refers to hell as Gehenna, it’s Christ himself. Christ used the term Gehenna (which you are correct, it is another name for the Valley of Ge-Hinnom) to illustrate the eternal suffering of Hell
:bible1: “And if your eye causes you to sin, pluck it out. Better for you to enter into the kingdom of God with one eye than with two eyes to be thrown into Gehenna” Mark 9:47
Christ sets up Gehenna as the opposite of the Kingdom of God. Therefore, interchanging the terms hell and Gehenna remains accurate.
2.) You say that Sheol was a comfortless place, but not uncomfortable. Christ, however, speaks of Sheol when he tells the parable of the Rich Man and Lazarus.
:bible1: “Abraham replied, 'My child, remember that you received what was good during your lifetime while Lazarus likewise received what was bad; but now he is comforted here, whereas you are tormented.” Luke 16:25
Sounds like there are pretty disparate levels of comfort in the netherworld afterall.