Not difficult with one set of stairs, but can be difficult with multiple sets of stairs on one map. I havent tried by just eventing. Also add into the mix getting NPCs to work properly on stairs and an Event solution is no longer quite as easy. Then making Events on stairs trigger, handling collisions, etc, and Event just cant cut it.
Doesnt really matter since I already wrote the script (out of boredom), but was just curious if there were any other solutions out there that I could check out. If there arent any, I'll have to release 2 versions of the script. One standalone and one for the caterpillar due to the way collisions and triggers are handled.