Whenever I have used a barghest against my players, they always wipe the floor with him and his goblin stooges. These have ususally been fighter heavy parties, however. Without someone to hold the line against the group your party faced, they would have a tough time against the barghest and goblins, any one or two of which would be able to greatly hurt your party in melee. With the party you described, I would think they should immediately run any time their clever plan doesn't work, as they have no one to suck up melee damage.
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