The higher delay there is on a weapon, the less TP is given to the mob over time. The job that gives the most TP to a mob is THF, and NIN before they got subtle blow.
And while on the subject of doing more damage... wiht haste gear, he might get a hit in 1 sec before the mob dies, which he wouldn't have done without haste gear, in which case he just magically did do more damage.
Either way, the reason most people like haste is to attack faster, thus killing mobs faster, thus increasing exp/hr, not getting an extra hit in. I do agree on 1 point though, and that is that DRK shouldn't concentrate on haste gear. They're there to hit slow and hard, not faster and weaker. And with Absorb TP, they can still SC almost once per fight, so hitting faster wouldn't be that usefull sicne they'd still attack rather slow.
Edit: Since you like numbers so much, let's play with numbers, shall we?
Let's say a fight lasts 50 sec.
60 delay = 1 sec. So with a 60 delay weapon, you'd attack 50 times. Now, fastest normal weapon is 180 delay. That's 1 attack every 3 sec, or 16 (16,66) attacks without dual wield or any haste gear.
I do believe Dayner said earlier that scythe is 525 delay. That's 1 attack every 8,75 sec without any haste gear, meaning he'd hit 5 (5,71) times during a 45 sec fight. That's 5x15 = 75 TP assuming he hits all of them.
Now, if we added some haste gear to that, let's say 5% haste. In first example, it brings us to 171 delay, meaning 1 attack every 2,85 seconds, which gives us 17 (17,54) attacks during the same fight. That's an extra hit right there that you got in before the mob died.
In the second example, it brings us down to 498,75 delay. Let's make it 499. That's 1 attack every 8,31 sec, meaning with 5% haste, he'd hit 6 (6,01) times in the same 50 sec fight. As you can see, with both a 180 delay weapon and a 525 delay weapon, both got an extra attack in due to just attacking not even a second earlier per hit.