I've actually found sometimes healers dps-ing is a necessity to even complete the floors. Last night I had a 6k HP MRD (yes, MRD) and 7k HP NIN on floors 61-70. Both myself as a WHM and the AST had around 9k HP. No aggro was held, multiple NIN and MRD deaths, many uses of witching pomanders (thank god for those) - we finally completed it, but both the AST and I were the top of the dps charts. I think the minimum requirement for aetherial level needs to be higher for 51+ and also job stones absolutely required...