I have mostly BCIs but I do have a baby Dumerils as well. First off, a male BCI will grow up to be roughly the same size as a Dumerils. Both will max out around 6-7ft and therefore are a fairly managable size. Really, you can't go wrong with either one. Both are very intelligent and curious snakes and both should grip you firmly - both as babies and as adults. Some have different ways of gripping though, so that is sometimes a very individual thing. My male BCI is constantly wrapped around me and holds on tight. My female BCI needs more support from me and would actually allow herself to fall if I'm not careful. My Dumerils is somewhere in between.
I will say this about Dumerils - they have incredibly calm and gentle personalities. All my BCIs are great, but my Dum in particular is very docile. They can be so docile though that they are almost to the point of being shy. And sometimes baby Dums can be hard to get started feeding. My Dum didn't eat with me for the entire first month I had her. Even so, Dumerils are my first choice to recommend as a "step up" snake. However, my own first step up snake was a female BCI and I've never been sorry about that. So it truly is a matter of personal preferance and what you like.
What I would recommend is for you to go to an expo or somewhere where you can handle several BCI and Dum babies and pick out the one that really speaks to you - the one you just can leave without. That will be the best choice you can make!![]()