PvP is a solid part of fun for many gamers, I think that it will be better to open separated PvE and PvP servers.
Nobody talks about rewarding griefers, but, imo, "free PvP" must be implemented in game like CryoFall.
While I agree in principal (and you're talking to someone who *hates* PvP in an RPG) you have the issue of splitting the player-base and, honestly, you won't really make anyone happy. The PvP crowd is also split into groups. Open world PvP, RvR, Area based PvP (contested areas vs home areas). Whichever way you go most people will be unhappy. So lets see you offer a server for every taste then instead of a single server with 100 people you get 5 servers with 20. If the game is successful enough it can certain support favored servers but I think that is better served by world builders.
So, I don't know that offering different flavors is the way to go and there are significant problems with both. While PvP allows player griefting via being "ganked". Allows griefing as well (building things to preclude other players from accessing areas, training mobs into town etc etc) with the additional issue of not being able to retaliate.
I guess I'm saying I don't have a perfect answer. just wanted to voice my thoughts.