I never understood the rep Bullsnakes get for their defensiveness. I've picked up, taken their temp, measured, weighed, etc. a ton of wild Bulls (best weekend was over 20 Bulls -I'd have to check my notes for a hard number but certainly over 20) … Anyway, over the years I can only remember one of them putting up a decent effort into trying to bite me and even that old boy mellowed out without me having to restrain his melon while I took his stats. Only a few have hissed at me too...
Bulls are impressive snakes as adults and they have called to me many times but keeping wild ones for a couple weeks at a time for group trainings always tempered that idea. I decided I didn't want to dedicate the large size of the environment that I thought would be necessary due to their activity and their ability to rearrange an enclosure is impressive.
That being said, I'm sure a captive born one is somewhat different than their free brothers. Finding a reputable breeder willing to share his or her thoughts on the matter would probably be more help.