There are many more occasions speed is not an insta kill. due to always being able to shift and not always being able to water bucket MLG, this makes sense. the fall damage of leaping 40 is insane, while speed doesn't 'hurt' at all.
I definitely didn't say Lucky Islands is a greatly balanced gamemode. I see I did say the item would be too good, but I'll have to rephrase that: the item would be too unfair. nothing can be done about it, and in a chase, fight or even if you aren't paying attention and turn around or run away, you will jump 99% of the time, meaning you'll be killed. It's not about fighting without jumping, but when someone throws a potion at you, jumping is a usual reaction, which I find unfair to punish for.