If you read it he actually explains that you can change it for other doodads aswell and the changing of the floor tile is easy to do. Also, my system isn't made for 2 floors (where did you get that from?) because you can easily do a:
Unit Group Floors = All of the floor units in the building
Region Building = The region of the floor (make the furthest part of the stairs outside the region)
Event- A Unit Enters Region - "Building"
Condition- Z height of Unit = (Z height of a floor)
Action- Pick Every Unit in Floors:
If Picked Unit Z height = (Z height of that floor) then
Set Vertex Colouring of Picked Unit to 100%, 100%, 100%, 100%
else
DoNothing
Thats really, really simple and works for as many floors as you like...
Edit: If you really want me to prove you wrong I could always create a demo map