in my experience, mercy stroke is a good damage CD, kinda like the bard's misery's end for me. i don't use it for the heal but an added dps. also, even if they nerfed BfB as a cross class skill, the added 10% on your damage is still added damage. as for rotation, i only use dragon kick/twin snakes/demolish/touch of death whenever its about to fall off during the current rotation, yeah i clip debuffs and buffs, not sure if its the right thing to do though but my idea behind clipping debuffs is let's say you let demolish fall off on your current rotation, then you won't have a damage from demolish until you get to use it again, and i think that's a lot more loss than when you cap it.

hope this helps