I’m working to open source an FDTD engine we wrote in Julia. It is heavily based on meep and uses many of the meep semantics (chunking, heterogenous stencils, etc). We’ve also written it to work on many (distributed) GPU platforms.
I’ve started the process internally, but my company requires extensive privacy and legal reviews. So it will take some time.
Many of the pros you listed (eg multiple dispatch) indeed made writing something like this much much easier in Julia.
We’re hoping to engage the community once we get approval and can open source the code.