Personally I would rather more oGCDs to press. A haste buff instead makes Double Weaving incredibly more difficult/impossible for most which is a DPS loss in the end. DRKs speed being more intense double weave oGCD windows instead of a slightly faster 1 2 3 (4) is more fitting, especially with how hard and often DRK strikes in oGCD.

Also greatswords being faster GCD compared to GNB or PLD is :think:.

20CD "Low Blow", 30CD Dark Passenger ontop would align with DRKs per minute frenzy window, adding 2 more in said window and give 3 more presses inbetween said windows.