I'm currently working on complex vectors and matrices. I started to implement them independently (i.e. a new non-generic type ComplexMatrix and ComplexVector), but I agree that it would make sense to share a generic interface.
Unfortunately this might be a breaking change. I expect that by now most users work with the Matrix type directly instead of the interface, so it would not cause much code change on their side. But I assume it would still require a recompilation. Nevertheless, I think we should do it.