Whenever there's a discussion around final drives, my suggestion is to plot wheel torque vs wheel speed in each gear for all FD options.
There you can easily see at what speed ranges each FD is faster or slower.
Ultimately it's about how close your power curve can get to the optimal "wheel torque = constant * peak power / speed" curve that CVT provides.
Here's how those graphs look like, e.g. at 7:22