Let's find out.
A level 20 monk without Haste and without Wind IV will attack approximately 96 times per minute with the main hand.
A level 20 monk with Haste (or just the 15% Enhancement portion of Wind IV) will attack approximately 115 times per minute with the main hand.
Current level 20 monk in Wind IV:
128 attack rolls per minute with main hand + 128 attack rolls per minute with off hand = 256 attack rolls per minute
Proposed (110% main hand + 80% off hand) level 20 monk in Wind IV:
1.1*115 main hand attack rolls per minute + 0.8*115 off hand attack rolls per minute = 218 attack rolls per minute
Assuming a 5% chance to miss, a 10% chance to critically hit, and the use of the Henshin Mystic necklace...
Current Ki generation in a minute:
256*(2*0.85+3*0.1) = 512
Proposed Ki generation in a minute:
218*(2*0.85+3*0.1) = 436
So, the proposed ki generation with the stated build/gear will be around 85% of what it is currently (due to the lower number of attacks).