I'm going to try to word this very carefully because I don't want anyone to get the wrong impression.
I know several people who free handle boomers - mainly because they are a fairly intelligent animal that comes to recognize it's keeper fairly quickly.
While they practice this, they ALWAYS remove the animal from it's enclosure with a hook. Boomers condition to feed very rapidly and will quickly associate the opening of the cage with food. They often shoot out of their cages like arrows and/or hit anything entering them.
I own thrasops which are in the same family as dispholidus (and as juveniles are almost identical) and posses pretty much the same venom. The difference being that boomslangs have bigger/more flexible rear fangs and open their mouths about 180 degrees.
I would be a liar if I told you I didn't free handle my thrasops. I would also be a liar if I told you I had never been bitten. The difference being that because of their smaller/less effective dentition the chance of an envenomation is greatly reduced.
The point being that after keeping an almost identical species, I would never free handle a boomer. A good bite from them is a trip to the emergency room instead of some neosporin, a bandage and aspirin.
The trick with some of the dispholidines (notably dispholidus and thrasops) is to remember that at their core they are nervous and fast animals. They move in erratic and unpredictable ways when agitated and will strike repeatedly. They can be incredibly accurate too.
Whatever you decide, be careful.