Here's how I see it. Can you powerlevel your character from 40 to 50?
I don't think so. Those levels are where the players are essentially forced to PLAY their class, as opposed to being complete brainless dolts when it comes to doing Dzemael Darkhold or other high-end content.
So it has a bit of a balance to it. Powerleveling allows low level players to "catch up" and find more people to normally level with once they reach Level 30.
In fact, powerleveling starts to lose its value past Level 30, as far as I know. I've done two powerlevel parties for a linkshell, and I always made it a point that everyone in my party have their equipped class be below 30 so that everyone continued to receive experience equally.
Also, I don't run powerlevel parties with three 50's, that is a little retarded in my book; instead, my powerlevel parties have only one 50, and seven sub-30 players. That way, the progression as well as how the PL does his thing, forces the party to practice their healing skills.
If they can't heal the PL to keep the EXP flow coming, they aren't worth PLing. :3









