Enmity is never a problem,unless you suck at playing. End of Story. I hold enmity EASILY over VASTLY out geared players. (Out gearing ME, not just content) When I had 4 iLvL 90 gear pieces, including the Weapon, I held Titan over a Full 90 + Allagan Bow Bard. No, he didn't hold back at all. Yes, he is a good player, and yes he out damage the entire group by 20% more than 2nd on Damage. I was consistently above this person't threat level by a good margin.
As for Role builds: That's where I would argue with you about your opinion. BTW You just listed more than 50% of the content while saying "Aside from..." So.. I chuckled a little there. So basically, your saying Turn 4 is the only fight end game that you don't need to be geared the same?
I feel that an Off tank should not be geared at ALL the same as an MT.
I have 3 armor sets currently. MT, OT, and DPS/OT.
If your not actively tanking something why would you want to gimp your potential DPS in any significant way?
IMO, BiS for OT Warrior is Hero's Belt of Fending since I'd rather have the Determination as an OT than Parry. But if I was the MT, I'd take Allagan.
If your MTing Twintania, You still always want to have a HUGE HP Pool Just in case something prevents you from putting up your Mitigation in time. (Pacification from Berserk for example, or having used unchained at the wrong moment.) Twintania will still smack you for 7800 if you don't manage to toss out that IB at the right time whle Vengence is on CD.
If your an OT for Twintania, the 3 Dragons are very weak, so you don't need all that MT mitigation and HP to deal with them. Defiance alone does the trick, and toss out a Vengence at the start to mitigate from 3 of them. After that, it's full on DPS to burn them down quickly. Then it's on to...... You guessed, it being 2nd on Aggro, and Dealing as much DPS as possible to Twintania in order to end the forsaken fight. At that point, ALL of your mitigation skills are borderline worthless, as you won't be taking threat on Twintania, unless your group failed. if you mention Snakes now, the Big Snake is for the MT, the 4 little ones are easy, and I have accidentally tanked them perfectly fine in Sword Oath when I was forced to play my undergeared Paladin. (Which means I was playing as a 6.3K HP Flash bot with no mitigation aside from Shield Blocks)