I wonder though if it's true about boss monsters never leaving the room they protect, I have a weird feeling that there might be bosses that don't protect a room ? What if this one is one of those ?
I agree about the assassins guild, they played out the PK system quite well, although people killing people knowing they die in real life make you think twice about it, but I guess some people don't have some restraints.
I always hated PVP systems in online games except RO, RO was incredibly fun and remains my ONLINE GAME OF THE DECADE. Nothing topped it yet

Similarities between RO and SAO are big, which is why I am constantly reminiscing the times I played RO when I watch SAO

I also would love to play SAO, there will be a game for PSVita released in 2013 if i'm not mistaken.