Mind me interveening in this discussion but i come here to represent the Rp friendly PvPer party.
On the grieffing part. You can organise RP events without being bothered much. Lots of guards everywhere, not that many players, and disccretion and such make it easier to have RP in open-world with minimal disturbance.
But regarding actual RP-PvP. What needs to be concieved is that PvP has some vectors that can't be dealt with easily and collide with the classical way of RPing (standing in front of someone and talking). That being you need to adapt and be tolerant to disturbance, clumbsy RPers or random grieffers.
The intrest of RP-PvP lies in two main things in my opinion. First it avoids what we use to call "the superman RP". You can't imagine the number of those their were in 2008/9. It was just silly to RP with them and swinging your hammer twoards their skull was what they deserved ! Second is the RP-PvP geo-politic.
RP-PvP geo-politics grants you the opportunity to PvP with attacking without having to talk for 15minuts and lose the advantages of surprise and first blow.
And RP argument between two players in a taverne could lead to an open-war between two guilds. The world was lively and their was a guild scale RP that led most of the guild wars. This made the world lively. Let me take a concret example.
During the first years we had this guild called Naerth, heavy PvP guild but with also a RP background story. They called themselves the Naerth Empire. Wrote RP announcements on Forum, the most known was that Conan, had personnally delegated the protection of Tesso to Naerth and thus the City was now under their law.
Three réaction possible:
1- Meh they are just brigands misinforming us ! Lets kick them out.
2- Oh well if conan said so i'll do as i'm told
3- OMG just stop playing, this isn't RP, it makes no sense, Conan would never have done that, and blablabla and blablabla.
Option 3 was sadly widely used and brings here the dilemma of RP and PvP. Integrate or Exclude ? If you played it cool and didn't exclude you could have both fun PvP in open-world and RP subjects to talk with and missions to lead or RP diplomatie chats. For instance i remember going with two guildie on a Naerth leader hunt and we led that in RP ofc was pretty fun and didn't feel as pointless as what i've mentionned earlier, the tea party RP.
Of course not everyone in Naerth was a RP, some where even complete morons but kept on a short leach by officers so a minor disturbance. Some weren't RPers but tried and some where. Here again, either the "true" RPers integrated them, or they were too far up their ass and excluded.
So what's RP-PvP ? It's an environnement, feeding RP as much as RP feeds PvP. But it requires tolerance and patience aswell as being able to adapt and not squeal because your char got spanked and that's not possible he defeated strom, the GGG, he can't get spanked just like that on a whim of an other character you spat on !
These days were awesome when you were into RP and PvP because both were linked an RP wasn't just a parenthesis detached from the rest of your gaming experience. We had guilds claiming zones and gathering there before heading to BRC or sieges. We had rivalries and pride. Epic battles and scheming.
When the "Emperor" of the Naerth "Empire" organized his wedding in an open-world zone all hell broke loose and blood was spilled other 5 diffrent maps. With RP-PvP you're choices have an impact on where you can go what you can do who you might face and who might want to retaliate.
Don't get me wrong, on that server not everyone where RPers but almost all the guilds had leaders RPing a bit and the only one that didn't was the vilain and everything worked well if you were tolerant enough to deal with the constraint enable open-world have.
Woot ! Wall of text ! It's so late i hope i made sense haha