I might have some decent input here as I ride a K2 Parkstar (both 2011 and 1012 models) and my brother rides a Rome Artifact Rocker (2012 model). First off let me start by saying that the Artifact Rocker IS a complete noodle, it's seriously ridiculous. If you're only using it for jibs and jumps smaller than 20 feet and buttering around smaller hills, it will dominate for you. If you want a bit more well rounded board, look somewhere else. The K2 WWW Rocker is basically K2's Artifact Rocker. They are very close to the same board. Slight differences in technology, but you won't notice much difference. I love my k2 Parkstars (which is why I bought another one). It has a very comfortable flex for me (I'm on a 152 at 160 lbs). I feel like it can do everything the Artifact can do and more. It won't have that immediate "lift your foot and the board comes right up" that the Artifact has but it's still easy to press and butter. The Parkstar has noticeably better pop off jumps and is surprisingly stable at higher speeds (I probably don't go much over 30-40 mph tops, but it does just fine for that). The Parkstar is a surprisingly fast board probably because of the sintered base. I destroy my brothers Artifact and my friends Burton Dominant when it comes to speed, it isn't even funny. As far as durability goes, I can only speak from my/my bro's experiences. Both my boards got several minor nicks around the edges of the topsheet, but the bases are super clean (again because they're sintered). My bro's Artifact has split and delaminated the topsheet on both the nose and the tail and again a 3rd time after one was epoxied back down. The base has deeper/more noticeable scratches as well.
In short, I'd consider the Artifact Rocker as more of a street board that you use for a couple rails at a time that is able to be ridden on the mountain (more suitably a smaller local hill) as well. The Parkstar is a great all around park board that is a bit stiffer to allow you to manage all around the mountain while being soft for easy presses and butters. A lot of info here, hope it helps.