Years ago my first, and at that time only, run in with a Boa was not pleasant. It was long (at least 150'), fat (slightly larger than a tractor tire), and MEAN! Ok so maybe I'm exaggerating the size of the beast, but it was mean. That much I remember. It really turned me off on boas for a long, long time.
Many years later I just got my own baby columbian RTB after having the chance to spend some time handling a couple of full grown adults and learning how mellow they really are. Not mellow as in they don't move, but mellow as in they aren't nippy and aren't trying to tag you every 2 second. They're awesome snakes and I would gladly recommend one to anyone who wanted a step up from a "beginner" snake