NG+ giving EXP sounds like a huge exploit for redoing scenario quests to gain levels. You could just keep doing easy "go here, talk to this NPC" quests over and over to get free EXP, which would be pretty cheesy.

In terms of using it, huge *yes* for me. This is a fantastic way to enjoy an entire expansion's worth of story content as at fast a pace as you want, and I haven't played through the previous expansions' quests in years.