i wasn't necessarily think K'Ehleyr as replacing Troi as counselor...more like her place at Picard's side on the bridge.
Troi's role there has been (it seems) like stating th eobvious, with no real benefit form her empathic powers. K'Ehleyr could do the same thing by listening to voices and watching expressions.
i think K'Ehleyr would have created dramatic tension among the crew...enough to for us to appreciate cultural diversity (as Pulaski seemed to do)