I just finished routing it in tas:
used EU color version to minimize lag, but it would be the same on gameboy, just slower because of more lag.
only difference between hard mode and not hard mode is more enemies downgrade your whip. The spawns are the same, same health, deals the same amount of damage.
From what I can tell, the enemies other than the normal spitter bubbles that downgrade your whip are:
birds eyeballs big bats
which makes the route in plant castle a little different because of the eyeball bridges, other than that stage though hard mode doesn't change anything for the route.
My opinion on the whole hard mode thing - it isn't challenging enough, it just arbitrarily extends the category by a couple of seconds (didn't actually test the difference) by taking a different route in ONE room of the entire game. Even then you could still take the normal route and just get two more orbs. It doesn't change the routing enough. Now, if ALL enemies downgraded you, different story. But as it is, it just makes the category slower with no extra challenge.
Hard mode also isn't viable for a low% run, since then you'd be running on leather whip always anyway.
So from me it's a YES vote for whip only, but a NO vote for hard mode.
