The Kennedy version's Countdown Round gave the leader 3 questions to answer, while second and third place had to answer 4 and 5, respectively. So, this version made it especially important to finish first since, then, you could potentially win the game in one round, while the others needed at least two. I thought it was, as you put it, a clever way to play catch-up since it wasn't impossible to win being in third place, but it did give a fairly significant advantage to the leader.
Hall's version essentially made the other two rounds irrelevant, IMO, since the leader had to answer 4, second 5, and third 6. Thus, everyone would take at least two rounds to win, so I didn't see a significant advantage in finishing first.
One other gripe about Hall's version: I totally understand why they changed the rule that they had to wait until the question was finished being read to buzz in (encourage more play-along and not be annoyed with dings along the way), but I felt that took an interesting rule out of Kennedy's. Namely, do you buzz in early thinking you know what the question will be, or wait to hear the whole question, assuring you'll get something, but you might not be first to ring in?
Anthony