I understand the house edge at BJ to be about 1.4% if players make perfect decisions.

A lot of Party players are not only incapable of that, but the accessability of the blackjack table will probably cause some of them to blow off their rolls in one sitting. I don't think this will have too bad an effect on mid-limit players. Most break even, play the cards, rake beaters differentiate poker from other forms of gambling and will keep winning money from lower limits and losing it to other players when they try to move up.