So with the recent NIN influx, I broke down while leveling mine and just got some randoms together in order to 4-DPS attack the Lv1-20 DF dungeons. 4 Rogue DPS only.
And it was probably the most fun i've had on this game since it was fresh to me:
1) First off, cross-class abilities are more impactful than they'll ever be otherwise. Skills like Cure, Protect and Stoneskin were immediately useful. Defensive CDs like Keen Flurry and Featherfoot are great, as well as the DPS ones for burning down mobs. We found ourselves changing and reorganizing them a bit.
2) There is no designated tank (because you'll probably just die), so managing Enmity is a party-wide endeavor. Meaning, you probably wont fall asleep during the dungeon like usual.
3) There is no designated Healer, so again, this is a party-wide job. Everyone keeps everyone else alive. It's the most amazing thing to come a few HP from death, only to be saved by your alert teammates. It's literally like playing one of the older Final Fantasy RPGs on ATB.
4) Items actually become useful, and for more than DPS checks. Totorak's poison ticks were a huge issue, until we realized that, oh yeah, there are unused Antidotes in my inventory which will likely be the difference between life or death. (It was, on more than one instance. 15 damage ticks are a huge deal with your hp is low and everyone's cure amount sucks.)
5) There is no feeling quite like fighting a boss you just know is impossible to defeat, until you and your teammates try that last-ditch, 7th-wipe strategy that just so happened to work. (kiting and enmity switching on the nine-tails)
So it's really a shame that after a certain level, this just becomes completely impossible because the enemies hit harder than a non-tank can manage to survive and a non-healer can manage to heal. It's such a pity, because queuing as a DPS is just terrible, and this was a really great pasttime while it was possible.