The performance gain isn't that much flat out, in day to day having the right gear all the time will be the advantage.
Right now with the JATCO five speed auto first and fifth gear are useless, you can take corners fast enought that you will be above the maximum downshift speed and the ford engine doesn't have that much bottom end (<4000), keeping fifth for highway cruise.
Now with the AisinWarner 6A, you discard 1st, and 6th, leaving 4 beautifully spaced ratios. the new 2nd is a smidge shorter, so is 3, the new 4th is way better for highspeed hijinx (85-115), and if uncoverned, 140 is doable in the new 5th, and you can 'cruise' at 125 in 6th (basically floored)
And with all the shifting, the 5speed stick is still a little faster and quicker in the 1/4