Trust me get a boa constrictor- large, laid back and hardy. In my personal opinion, carpets can be a bit nippy and have a super nasty bite when they get larger. However, they are stunning, especially some of the new morphs that are available. From what I have heard from SD retic owners is that they can either be sweet or aggressive, but always come with an extreme feeding response- basically same insight as normal retics! I have no experience with Dumerils. You can purchase and "create", if you will, by proper handling and through time, very tame individuals of the species you mentioned, but in general, boa constrictors, BCC or BCI, are laid back. I have kept many species of snakes and for anybody who wants a larger but sweet snake they are always what I recommend. However there is also something to be said for individuality. I have one female BCI who would just as soon bite me as look at me, an amazingly sweet green anaconda, and a ball python who thinks he's a cobra. I hope this helped and sorry if it didn't. Basically, all snakes are individuals but in general, a BCC or BCI will make a wonderful, laidback and impressive snake.