Hands free would be great for highways, although if it has a hard time, like now, keeping centered in the lane while negotiating sharp turns, it could be a disaster.
I often drive one way about 200 miles through the mountains from Tucson to Pinetop, and HA works pretty well. The major issue I have is that I need to jiggle the steering wheel too much: because DDP allows you to make some lane adjustments by moving the steering wheel slightly, it's annoying to have to give it a proper tug. Four hours of that gets old quickly.
I've been using one of my Teslas with FSD more often now to make the trip. I can go from door to door without touching the wheel once, including negotiating all the curves and city driving. Hands-free DDP, along with Street and Highway Pilot, would go a long way in allowing me to make the drive while resting my hands and enjoying the scenery stress-free.