From the other thread.
Technically, you are +16, not including a few frames to get out of the way completely. 3 isn't a true high and will usually hit anyway. If it was a high, it should be guaranteed, provided the hit box makes contact.. It seems that few characters can actually do this while stand blocking the first hit. Sindel & Kitana only?
If a sai is used immediately (it usually is) and you of course crouch block the second hit, the disadvantage is more on the teleport. You can use 2~ex fan which is easier to do than d1~ex fan.
edit: not that d1~ex fan is that hard, but it is more damage.