The biggest issue is that people get into 51 and above and keep trying to run as if it was lvl 1-50. That just won't work. I finished multiple times with no Tank but I have to admit that with no healer it is a bit frustrating because the ubber (in their mind only) NIN's and DRG's seem to think that they are immune to death. I once wiped 6 times in a row before we cleared 3 times in a row. So team work is what gets you through 51-100 the gear does help as long as it is over 30 and it scales up pretty quick once you are able to finish floors, and clear bosses.