it could just be my bitter side talking because I don't have a great lvl 70 class help me lvl up but I think power leveling your chars to lvl 40+ and then trying to manage them on your own could pose a bit of a shock with instances or harder quests when all they've did is follow a 70 around for a few hours. Unless you've played the class before, you have a dozen+ skills you've never tried to use effectively and macro's you've never taken advantage of except /follow. with 2.3's level xp reduction and quest xp gain I've been able to level on average in just under 2 hours per level making sure I do good chain quest and stay away from tedious collection quests. It's certainly slower than having a mage clear SM over and over, but it feels good to learn play my chars effectively, manage their mana and keep them all alive while I level