I'm not crazy about Darvin, I'm not sure what it is, but something about the sound.I do love Darwin though, or rather I love the meaning. And Davin is kind of cute as well : )
Darvin sounds like a German (which Mom's ancestors were) person saying Darwin. Davin, I really don't like for some reason. Darwin is nice (I like the meaning), but I don't think DH would go for it.