That's what I had at first. Up until lvl 65, the shaman and bard buffs were ENTIRELY redundant. Only thing the shaman brought to the table was slow, malo, and snare, which weren't really that important for normal mobs, and the bard can do all that anyway to some extent. A couple of times he spammed a few emergency heals to help out the merc cleric, but that was in a very few situations in which I knew I had screwed up already.
Got my rogue/bard/SK team up to 70 now on test. SK is working out nominally better than shaman. The merc tank is still super solid (helps to have J1 now), so all the SK adds is a bit of dps and once an hour he can obliterate a red con with HS. But I can start to see his tanking potential at higher levels.