Actually, you don't understand how dots work. Haste breakpoints don't shorten the time between ticks. Haste does. Every single point of Haste decreases the interval between your ticks. The only thing that happens when you reach a "breakpoint" is that the duration is reset to it's initial length (which is pointless when you have pandemic).I'm sorry, but I'm afraid you simply don't understand how haste breakpoints work. They shorten the time between ticks, which has nothing to do with Pandemic or the DoT running out.
No. Just, no...i.e. Troll, Herb / Engi.
Realistically, Engi/Tailoring/BS are the 3 "best" proffs out there for any dotclasses (ahead of the other static 320 Int perk proffs). Herbalism is dogshit and only above Mining and Skinning, why would you even consider it?