I've been cross-country and over some serious passes in the Rockies and Sierras.

However, it's comparing apples and oranges. There's no "downshifting" and intentionally "running max rpm" with this vehicle. It will do what it needs to do to deliver the required torque, and going up steep grades at speed generally means max torque. You'll probably see the RPMs go way up... essentially maxing out, and you'll likely get whatever electric boost is available until it runs out.

I've found that my FEH does have the balls, but you may no longer want to maintain that speed up these grades when you see in real time what it's doing to your mileage.