I don't think the roles concept is a problem, I think it's a strength. All out PvP has never really worked. It may seem artificial but I think you need some degree of controls in PvP for it to be successful - DE's roles look like an interesting way of doing things.
yes the idea is good, I just think there's always going to be a shortage of one role thats played that will unbalance the pvp system and make it less fun.
Like the presence of a major clan that are primarily bounty hunters, if they get too strong then noone will bother being an outlaw, except for killing venerated mobs only. Doing trade runs between cities will be too easy and DE will seem very bland without any presence of a threat to a particular role, and will lose one of its major selling points - meaningful pvp.
This is an extreme example but this sort of BH's target outlaws, outlaws target traders approach is just a little too restrictive and almost impossible to balance. You cant force people into a particular role which has a major shortage.
Its going to be important to choose a good server, some will be very boring places I'm guessing - full of alliances between clans/cities - meaning less city battles, safe trading etc clans on a server could make it almost a pvp free environment. Horizons reborn