I heard if you get to 70 and then fail the rank up dungeon it takes about an hour to de-level 1 level. That's like tacking an extra 15 minutes per run which is kind of painful, plus it's stupidly boring to do this for an hour straight considering you can only do 3-4 runs before having to do it (source: the other popular cabal forums).

Is there a better way to de-level in the level 60-70 range?