I would definitely rank it up there as one of the worst beats in poker history for a couple of reasons. There were pretty deep in the MAIN EVENT at this point, top 15 I believe. Also the fact that Duhamel went on to win the title that year leaves a really sick feeling in Affleck's stomach. He probably still thinks about it to this day, how much differently his life would be had he won that pot. He might even have himself convinced that he would've been the winner not Duhamel.
Although the quads A's vs Royal Flush is a very sick beat, it wasn't nearly as deep into the tournament.
You have to consider the context, not just the cards, when considering a hand as the 'worst ever'.
Definitely up there, but not worst of all time.