Yeah, I'm trying to convince Oda and Campitor to remove the warp option entirely. Possibly replace it with a party finder option which would educate players about the party booking system.
It would be great if, when you select the teleport option, the signboard says something like, "Signs can't use skills. If you need to find these monsters visit db.irowiki.org and see if you can find a priest to warp you."
I gotta say, I do like the implications this provides for partying. Also, I agree that these billboards would definitely work better without Gramps, though if Gramps goes the way of the dinosaurs, I would like to see monsters with related billboard quests get a significant spawn increase where needed. The current billboards are a great example of an appropriate amount of monsters on a map. I think that if you don't have enough, it'll end up becoming really difficult to complete the billboards, especially if you factor in the amount of people doing them once Gramps is gone.