I'm not sure why people would want this:
Roaming Dragons.
Giant Beasts.
High Respawn Timers.
Amazing Gear.
There's no skill to be gained from having more time to spare then others, which is really all it comes down to. Was Team A really better then Team B cause Team A could spend 12hrs waiting for a spawn while Team B could only spare 6? The whole idea behind 14 is to do away with the unnecessary time sinks which kill the fun of the game and only cause rifts between the community as well as create dead times in a game in which you would want to be active and actually doing something. there's really no need to bring a concept like this into the game. Why wait for something to spawn, when you could easily do something as simple as this.
Use guild leves as a means to obtain rare spawn items for unique roaming creatures. Rather then one set point for a spawn, create lore within the towns that give you hints of the current location of the beast based on the rumors going around. To make it a tad trickier make it where some NPCs may lie. It's better to create a concept for HNMs that's more active rather then one that makes everyone passive just waiting for the encounter to happen. Do real adventurers wait for a best to appear in front of them or do they hunt and seek out that which they want to conquer? The idea behind finding said beast could be easy to.
You obtained "gnawed tusk" from a leve that has distinct teeth marks which others may know about. When you go into the outside towns and talk to the NPCs, you'll be given the option of "Discuss gnawed tusk" which will then prompt them to give you input on the item and either direct you to another NPC, direct you to a location, or lie to you. From this point each NPC would have to be analayzed for their personality and how they react to each KI for each mob spawn. The experience would allow hardcore players to map out the behaviors of each NPC so that they can have an edge on finding the spawn point while the casual will have to take more time in discovering the location. Rather then create a respawn timer for said creatures there could be a fatigue for anyone involved in fighting the HNM, since it's an HNM I think it's only fair to say that fighting such a beast would put stress on the party would it really make any sense if they were able to just continue spamming the same best over the period of 2-3hrs?
But ya I"m just saying there are more active ways to create an HNM system, it doesn't need to be a carbon copy of 11, the whole concept behind respawn timers is to create an unnecessary time sink and judging from the current path of 14 I'd say they are attempting to do everything in their power to create unnecessary sinks which cause players to idle in wait for an encounter with an NM.