It doesn't make sense to lose the function keys, the more keys the better (though i'd argue that it's better for less frequently used functions where it's easier to remember spatial position while not wasting much by moving your hands), though for arrows it's definitely more comfortable to have home row arrow keys with some thumb prefix, you can even have up/downs by various distance (e.g., "jk" for arrow down/up, "m," for pageDown/Up, and maybe "ui" for some "up to home/down to end") so that your same down/up muscle memory in your same two fingers