Gearing options being equal, DNC should not really outparse THF when they're in a party together because all of DNC's advantages are party-wide buffs or alliance-wide debuffs or are directly balanced out by something THF gets.
* Haste Samba is party-wide
* Box Step / Quick Step / Feather Step (depending on situation) are alliance-wide
* 25-20% DA from Saber Dance = 11% TA
* Accuracy Bonus III and Closed Position vs. Feint half the time
Harder to quantify:
* Terpsichore PK spam vs. TA Mercy Stroke every 50 seconds and SA Mercy Stroke when the situation allows it
* Treasure Hunter vs. greater durability when the situation calls for it
If you were worried that about your damage output and had a good player with both jobs pimped out, you should bring their Dancer for Haste Samba and to have someone that will actually land Steps. However, if they could parse against themselves then I'd be unsurprised if the THF won.
As far as Skillchains being viable, it's true that I don't always complete self-skillchains that I attempt in groups, but keeping an eye on TParty and seeing when it's possible to skillchain does have its advantages:
Code:
Dmg: Byrth 54692(38.2%), RNG 33648(23.5%), PLD 20991(14.7%), MNK 20439(14.3%)
Skillchain(Byr.) 12440(8.7%), Skillchain(PLD) 562(0.4%), COR 414(0.3%)
Disclaimers:
1) This was an AA MR normal shout group without a bard. It's obviously a less than ideal parsing situation that makes skillchaining a little easier, but if you keep an eye on the most recently used WS and know skillchain properties, it's possible for any DD to milk a little more damage out of it. In groups with Marches, most of the WSs you will be skillchaining off of will not be your own, so there's no real advantage for DNC there.
2) I'm super rusty. I made a 99 Daurd/G-horn in September or so and didn't play anything else in parties until I finished Terpsichore last week.
3) I spent about half the fight using Fan Dance and was charmed from 25-10%. My hit rate was also pretty shit due to the lack of madrigals (~77% even when maintaining Quickstep, PK, and Rudra's and eating Sushi) and if I was doing it over then I'd probably just use AM1 instead of maintaining AM3. That said, this was a situation where Feint would have been very useful because the MNK and PLD were parsing 50% hit rate or lower.