@Arlathen, it's all about the synergies between THF and U14 changes. Anything that grants +W's is inherently benefitting base dice like eAGA and eSoS much more than any endgame 1 hander, though I would say that Nightmare would be close. Several of the benefits you mention are worthy considerations indeed, but I'm confident you'll agree that the changes to cleave + ED synergies outweigh those benefits whenever you're able to test it for yourself.
Beyond weapon weight benefits, the "secret" x-factor would be Wild Weapons. Not that compelling on paper, but test it in game and you'll see what I mean. I'd wager that a tempest ranger could respec tempest feats for thf feats and come out ahead using thf.
Barbs obliterate palis through level 20, but so much extra damage potential now comes from ED's, which any class with the required feats could benefit from. Most barbs seem to think Horc is the way to go, while palis tend to be human. That alone accounts for much of the narrowness in the DPS gap as humans destroy Horcs while boosts remain (due to dual boosting haste and damage), and there are very few situations where you'll make it through 10-12 (more for kensai) boosts before being able to shrine or simply finishing the quest.