Yes, I think we all agree the most important thing about implementing this cool idea is to maintain the status quo for walking around in the world (in turn maintaining world pvp, danger in transporting valuables, and the Port market).
At the end of the day, this will be done by limiting the number of blocks total that each individual engineer can be responsible for. I will call that "individual Engineer total teleport potential" (measured in blocks traveled).
Obviously the issue people see is safe, non-pvp travel. I do not think that a determined town would be incapapble of doing this, but as long as we make it hard enough, no one will. If a town wants a teleport chain to their town (lets assume its at least 1000 out from spawn for arguments sake) they need:
A) five plus engineers minimum (making the max range of each Engineer's total teleport potential ~100-200 would serve well to moderate this)
B) Each engineer would lose all teleports placed when changing profession to anything other than Engineer.
C) Combat tags should prevent using the teleport.
D) the reagent cost should be high enough that engineers Think about were they put teleports, rather than just place them all the time and creating new routes. Nether fence works pretty well to do this for turrets, but would not be high enough here.
So a town with 5 active engineers, exactly 1000 blocks out, has an ok chance at trying it, but if their gold courier gets intercepted, he will be stuck with whoever tagged him as they camped his town's teleporter chain.
There are NO towns with 5 active engineers (plus most towns are farther and would require even more engineers), and the camping potential would greatly reduce the chance that it would be used to avoid pvp. If implemented and we Still see teleport chains, more disincentives would be created.
edit: engineer or mason
