I've read some of what other people have suggested, and I think there's some good stuff that's been suggested, many rule-sets that I think would work wonderfully, and I feel are just plain simpler and less exploitable than the "dynamic" pvp system. It was a great idea, it's just really difficult, and not worth the time and effort to test/code/develop/troubleshoot/police/etc. So, here's my feedback and suggestions:
I liked the hardcore rules on Sullon Zek that you could kill anyone on the other teams. That server was different though, because you had team-mates to back you up (supposedly), and also faction help you could fall back on like guards and class trainers and such (supposedly this is being worked on?). Without a team to rely on, and currently no assist from NPC's, there isn't going to be as much of a "safe" area for anyone, ruling out that type of no level limit rule-set. Thus, I suggest either a +-10/+-5 or +-8/+-4 ruleset similar to what a couple other people have mentioned. Let me explain the numbers.
In a 10/5 ruleset, 10 levels would be the engage range, while -5 is the loot/exp death range. You can freely attack anyone within a 10 level range of you, but you'd only be able to loot coin from or cause an experience death to someone 5 levels below you. If you manage to kill the player higher level than you (between 5-10 levels) they could still lose exp and be looted, as a penalty for sucking so bad (if that's easy to code/set up, if not, no biggy, basic +-10/+-5 is fine). If people think that's too hardcore, you could make it +-8/+-4, where 8 levels is the max engage range, but 4 levels it the loot/exp range.
In my mind, this system facilitates a higher amount of pvp engagement, while not making the penalty so severe for those getting stomped on by someone who is realistically way out of their league. Larger engage range, in my opinion, allows for more immersion
[You must be logged in to view images. Log in or Register.]. So would faction assist, for that matter.
Now, if you REALLY wanted to get tricky, you could do a scaling version of this ruleset, where at lower levels it's something like 6/3 (levels 1-10), then 8/4 (11-25 or 30), then 10/5 (26+ or 31+). Something along these lines would be ideal for this type of FFA server, in my opinion.
I'd actually like to request some feedback from everyone on this particular idea, both the X/Y idea and the scaling 6/3, 8/4, 10/5 range. To me these sound really good! What do you think?