Just from the practical side of things - if you have a Dumerils now and you have had only or predominately boids - before you get a bullsnake be prepared for the difference in metabolic rate. While they likely don't rival indigos for volume, bull snakes produce very abundant feces very often. People who are used to a boa going once every couple weeks are often dismayed by the amount of poo a bull snake can generate in a week! They are also very active and I think they need a larger cage than a comparable length boid to accomodate that. Their personaliites are great though, lots of bluff and even some attitude to back it up.
Best of luck on your choice,