Our package deals that I can recall all worked out pretty well - i.e., they didn't bring in anyone hobbitesque or anyone who caused major drama. It was usually chapter legacy + friend(s). Since we had deferred rush the whole package had usually met most of the sorority by the time recruitment rolled around anyway and it wasn't a matter of the legacy stomping her foot and insisting we take her buddy. I can't imagine doing this with pre-freshmen in fall formal rush and having sort-of-a-clue about one and no clue about the other.
If anything, sometimes the legacies were the semi-weak link and the ones who came in with them ended up being much more of a positive force in the chapter. Case in point: the legacy's best friend (at the time) who got much more festive once legacy graduated and who is the one who nagged us all onto facebook and reconnected us.
Really, I think it is a case-by-case situation.