Hard line it as much as you can, hard lines don't collapse or deteriorate over time and are impervious to modern fuels.
Have never understood why we can't have aluminium on the street, considering A/C lines are made of the same stuff.
A ruptured aluminium A/C line will dump a heap of PAG
oil which burns anyhow.
So the authorities would rather any hose over aluminium tube, even though the burst strength of the tube is superior.