I don't care what you've ridden. The data is well established, it's not just Zipp. Most companies who actually use wind tunnels and cfd to design their wheels have figured out that the best way to design a wheel is from the nose->out, with essentially a cut off blunt airfoil.

In Tour's most recent data, with data translated to 25mph, the Zipp 808 had an aero drag equivalent to 6.2 watts; the Hed Jet 9(similar shape but non parallel brake tracks) measured 9.3 watts and a deep V Cole rim(similar to what Boyd, et al use) measured 13 watts. All well outside of the margin of error for a good wind tunnel.

There are similar differences for shallower wheels. And actually, ironically enough, some of the shallower wheels can have greater disparities than the deeper wheels because shape and spokes matter more.

Anyway, to the OP, Bontrager has a new type of wheel out so anyone giving feedback on the old wheels may not be as relevant to your purchase because they changed from a carbon fairing construction to a solid rim like Zipp. Though, I also don't know what your LBS is trying to sell you. The difference between your carbones and the older 404 shape would be more about weight and less about aero.

I'd say that just about all the wheel companies using the new blunt inner edge, wide, curved walls should be a good step up from your Carbones. Enve, Bontrager, Hed, Zipp and Rolf are all using a newer rim shape like this.