Regarding hills: I have gone over some significant hills (e.g. from 0 to 4200 feet in 10 minutes) in my HCH CVT without experiencing any real difficulty. The IMA (electric motor) helped out for a while, but then was eventually used up. When it did, the engine did just fine, and I maintained a speed of 65 miles per hour in cruise control the entire way, passing many other autos (this was going over the grapevine in southern California), without making the engine work too hard.

I guess I point this out just to say that I have not personally experienced hill issues. I also know that I have read elsewhere that the FEH has fared well over hills, but I read that a while ago.

You might post your question in the FEH and Highlander groups (if you haven't done this already). And the advice to ask some locals full of wisdom as well.