The results are interesting. In the end, weapon speed doesn't make as much of a difference as I thought it would, except for swords. Fast attack speeds do bring up the average damage of small weapons. Of course, when you use the big 2H weapons most battles don't last that long, because when you factor in damage bonuses most monsters will fall with one or two blows from a big weapon. Bosses, though, that's a different story. For example, if you are stuck chopping away at Duriel for a while, you see the Grim Scythe will do nearly as much damage as the mighty Lance. Same thing for multiplayer games, where monster hit points are multiplied by the number of players in the game.
The most interesting results are for those weapons which do good damage and are fast. For example: for barbarians, the Zweihander does more damage over time than the Executioner Sword. So the Zweihander emerges as the new king of swords.
Also, the Ancient Axe is a bit faster than the Martel, but not enough to matter. Its average damage is 75% of the Martel for a single hit, and its time averaged damage is 88%. However, the Grim Scythe is much faster than the Martel. On average the Grim Scythe does 66% of the damage of a Lance and 57% of the damage of a Martel for a single hit, but time averaged it goes up to 89% and 78% respectively. That makes the Grim Scythe look pretty good, when you consider faster attack speeds mean you are less likely to get interrupted or stunlocked.
However, certain attacks like Jab and Whirlwind ignore weapon speed. In that case, time averaged damage is irrelevant. Use the Melee Weapon Stats table above for comparison instead. There you see Lance still gives a much better average damage than Grim Scythe for a Jabazon or Whirlwinder.