To people for whom layered arrows work great, I wonder how well gestures like shift-ctrl-left, shift-home, shift-ctrl-end work for you. I use those a lot; the split between left hand for selection and movement modifier, and right hand for the actual movement, feels highly usable due to its logical modularity.
Needing one more key (Fn) to access the movements seems to break my coodination capacity. I know it’s possible to combine modifier keys, but that doesn’t work well enough for me, I’m guessing because of how frequently I change the “chord”, almost on a per keystroke basis, depending on the word / row, intentions that jump between “mark this”, “not that”, “move the line without highlight”, etc.