I've been grinding my butt off more or less for 8 months and continue to do so. I'm looking forward to being done and not having to re-grind the "advanced" version of my job. From everything they've said these jobs will not be wildly different than the "basic" class form. You're not going to need to learn a radically new play style for them. What this game needs is content and questing, not ANOTHER grind.
