While I do not have a Dumerils (yet, lol), I do have a columbian boa and I absolutely LOVE her! She is incredibly curious, very sweet, highly intelligent, and loves to be handled and just hang out with me. What could be better?? Of course, I have heard that both Dumerils and Rainbows can be the same way. I personally think you'd be happy with any of these 3.

Male BCI will get about 5-7 feet and the females around 7-9. The rainbows will be about the same but will have a more slender body. The Dumerils will top out at about 7ft for a large female, but they are the most heavy bodied of the 3 so you're looking at about the same size for any of them unless you get a particularly large female BCI that pushes 10ft - that isn't likely, but it IS possible.

A proper enclosure would be a 4x2 cage for an adult of any of these 3. If you get a baby, it should be happy in a 20gal long for nearly it's entire first year so you'd have time to save for a larger enclosure if you went for a baby. I like this cage from PVC Cages. It is 48wx12tx24d and the perfect size for anything except the largest female BCIs. Also, if you order it with heat, it is a radient heat panel which is a marvelous way of heating from above. No UTHs! So you can set the cage directly on the floor.

Oh, by the way, all boas bear live young so they have "litters" not "clutches".