my first snake was a rtb and she's been an absolute joy. I bought her when she was about 1 month old, so she's still really small (23 inches), but they get to be anywhere from 4 to 8 feet (males are smaller than the females). She's not tempermental at all, hasnt nipped me once. great feeder, took f/t with no problems, eats regularly. had some problems keeping meals down at first, but i just didnt give her enough time to settle in.
they usually dont get really big until about 2 or 3 years old, so by then you'll have much more experience with snakes and can handle a larger boid.

hope this helps!