quote of the op:
"% DA Haste
00% - 0 - 0
05% - 5 - 5
10% - 10 - 11
15% - 15 - 18
20% - 20 - 25
25% - 25 - 33
30% - 30 - 43
35% - 35 - 54
40% - 40 - 67
45% - 45 - 82
50% - 50 - 100
55% - 55 - 122
60% - 60 - 150
65% - 65 - 186
70% - 70 - 233
75% - 75 - 300
80% - 80 - 400"

thx for this chart
20% haste (+25)+ 7% DA (+8)= 21-22% (assuming at one u get +27) haste + 5% DA (+6)= 25% haste (+33)

now adding haste spell

35% haste (+54) + 7% DA (+10) = +64
37% haste (assuming +57) + 5% DA (+7) = +64
40% haste = +67

conclusion:

at lower haste level u can rep some haste for DA, 20% haste + 8%+ DA and 22% haste + 6%+ DA will outdo 25% haste.
gonna hope SE will give more DA & TA gear to us in the future ^^