I'm curious as to what you don't like about them (other than wanting a bigger one).
I would like the 75 to be marginally bigger as it is very tight with the 1DX and 70-200 f/2.8 ii and I would like just a little more room at the top to make it easier to get the camera in and out. The things I do not like about the 75 are not important but do add up.
1) I would like a more substantial waist belt.
2) I would like them to put the 75 handle on the top like with the 55, or at least make the handle on the 75 a little more substantial.
3) I would like them to rearrange the zip of the top pocket. It is currently U-shaped (bottom of the U is towards the body) whereas I would prefer the U shape to be turned 90 degrees to the left so that the zip starts and finishes at the top left and bottom left of the bag.
4) I would like them to get rid of that small mesh pocket on the front pocket and replace it with a small zip pocket or preferably some real pen holders with a protective lid cover so it is not easy for the pens to be knocked out.
5) I would like the top pocket to be slightly larger and better compartmentalised. At the moment that is where I keep my spare 1DX battery, spare flash batteries, name cards, USB memory stick, and a few other things.
6) Make the mesh pocket on the side an expandable fully closed zip pocket.
7) An additional pocket at the bottom of the bag with padding purposefully made for a 1.4X or 2.0X extender
As I said, they are not major differences just small changes I would like to see, which of course is just my opinion and may not appeal to everyone. So perhaps a new 80AW is not needed, just a 75 Pro AW ii ;-)
Edited: Added Point 7.