Vinyl will cope with any minor changes in height between floorboards better than any wood- or cementitious tile backer board.
New vinyl will look good,
and,
if buyer does not like it, well they can change it.
Seems better than buyer cursing you for creaky tiles.
Kitchen = spills
spills + hardboard = rot.
Can you afford the thinnest marine ply,
or,
osb3, at 9mm,
http://www.jewson.co.uk/timber/sheet-materials/osb/osb3/
you can find?