I'm with Michael - 7 stings is just a message: "We're not amused, and you'd best just wrap this up." :-). I wonder if maybe they were dropped? Queen acceptance issues? It would be interesting to see how aggressive they are in a couple of months with new bees raised from the new queen.
I've only done two installs, no aggression, they just moved right in. A couple of days later, replaced the inner cover poultry feeder with no gear/veil/gloves/smoke, they just stared at me through the inner cover hole, waiting for Dad to give them some more food.
It was very Zen.