So far I've leveled drk (70) and I'm in the process of leveling pld (66), here's a brief summary of my overall experience:
1. AoE threat is a mess right now, period. Flash, Abyssal, and other AoE threat moves need an increase in their enmity modifier, maybe 15%-20% more and I think it will be fine as is.
2. Single target threat is fine, mostly. With a susano weapon, lahkshmi accessories, and tomestone gear in every slot I've had absolutely zero issues with single target threat.
3. I definitely notice the decrease in damage but I don't mind it so much, I still stance dance when I can and do my best to speed things up but for a lot of these dungeons some of the enemies hit so hard it's not an option.
4. Damage taken seems... I dunno inconsistent is the best way to describe it. Sometimes I'll pull and just while establishing threat from the initial pull I'm suddenly at less than half my hp even if I've popped a cooldown or two.
5. Drk absolutely felt incomplete and squishy as I was leveling it. Then I got it's 70 ability Blackest Night which is an insanely strong mitigation move and it's become a staple of my rotation very quickly. I underestimated just how strong the move is and that it's good in any situation whether you're MT or OT. Seriously, Blackest Night was a total gamechanger for me and I love drk now compared to my rather "meh" feelings towards it while leveling.
6. Pld felt less squishy than drk, more often I felt perfectly at ease going dps mode during dungeons. However, I can also attribute this to the fact I leveled Pld second and had become comfortable with the dungeons, layout, and trash so I better knew what to expect. I also didn't know healers could heal for as much as they do, burst healing seems to be pretty crazy.
7. Looking back at point 6, I think burst might be a little too out of control for damage taken and healing. This very quickly leads to a situation where mobs can hit for more than half your HP and every one has to be topped off at all times or die, not a good place to be.
Short version:
1. AoE threat needs a buff.
2. Single target threat is fine, mostly.
3. Drk doesn't feel complete until 70.
4. Pld is in a really good place.