I like my diseases tbh. That and pest really helps with aggro and just overall damage output. Generall I do not reapply diseases unless it is a boss.

In general though, how well do you have a hold on targets you are not directly attacking? While DnD does help grab some aggro and keeps generating more of it over time, I would assume it would not be as good as a disease using tank.

This of course is only my opinion so please speak up if you have a great counter-argument.

If the situation allows, I pull with DnD, then Outbreak on the main target, then Pestilance, then HS/DS/RS. I use BB when it procs free. No problem holding aggro on everything.

If Outbreak is on cooldown, I just move from DnD straight into HS/DS/RS spam. If there are more than three targets I usually will throw in a BB early too (even though it's not free).

I think the changes have sort of put the nail in the coffin for diseaseless tanking with the changes to Scarlet Fever. Blood Boil no longer applies the 10% damage debuff that this talent gives, but instead has it being applied through Plague Strike. This means both of your diseases now offer major debuffs as a tank that you should be taking advantage of in any fight. This is more so the case in multi-mob situations where the 20% attack speed debuff and the 10% damage debuff will help reduce the amount of incoming damage you take.

Diseaseless doesn't matter much in heroics one way or the other, from my experience, although I'd be tempted to use them more if I was just gearing up.

On the other hand, unless you have someone else *reliably* providing the melee slow and the physical damage debuff (a DPS DK, for example) then it's incumbent upon you to provide those debuffs. All you lose is 1 DS every minute or so (assuming 2/3 Epidemic) which isn't much when you consider that without those debuffs, raid bosses will be hitting you harder and faster at least 30 seconds out of every minute, and longer if you didn't put points into Epidemic.