I tested running Copperbell Mines at level 18 -- I was healer, not tank, so I didn't control the run's pace but did push things along by repeatedly outstripping tank enmity (rawr, healer DPS). Not the fastest run, but no deaths or wipes. 38 minutes to complete. Depending on whether you include the first-completion bonus, I hit either 951 experience per minute or 856 experience per minute. I'll run FATEs near Aleport tomorrow.