I own quite a few boas. I have Central American boas and Colombian boas. I do not own Dumerils or Rainbow boas, so can not comment on those. Central American boas stay very small. Males average around 3.5 feet and females 5 feet. Colombians, on the other hand, are quite a bit larger. Males average around 6 feet and females 8. If you were to get a Colombian red-tail, which is the most common red-tail, I suggest going with a male. Females can get rather large, and although they are usually very docile they could be tough for one person to handle. There are also many different colors and patters to choose from. Check out kingsnake.com classifieds for pics of different morphs. Good luck on whatever you decide.