This is my five floor realistic slime block piston elevator [comparavator 4.0]. It moves at 2.4 blocks per second, has automatic doors, and is multiplayer friendly.
(READ BEFORE USE): This elevator occasionally produces duplicated blocks and ghost blocks(1.8 bug), if this happens break the dupe/ghost blocks and the elevator will function normally.
Stand in the middle of the platform as the elevator moves upwards to prevent getting stuck in the blocks(1.8 bug).
Do not log out of the world as the elevator is moving, this breaks the redstone.