Example:
with 24% gear haste and 15% spell haste
30% da, 15% ta

You are looking at ~59 hits a min that you gain roughly 5.6tp for

Add in the 1% haste to bump you to 25% and you are looking at roughly, 60 hits a min

Add in 3% da/ta instead of the haste, (24% gear) and you are at 62 swings a min.

So in this example you are better off being at 24% gear haste (15% spell) and going for the extra da/ta