Well I guess my primary reason for the shaman is slow and healing. Dual cleric mercs can obviously handle healing, but what about slows? Bard slow is a pain in the ass, which is the only reason I wouldn't want a bard. Aside from that, the bard has no real negatives.
Is slowing still essential late game as it used to be? I was also considering sk/enc/wiz, but then I am losing tracking, but I know they synnergize really well together.