Reference counting is ultimately a GC, although not a tracing GC which is the most common kind. I also don't really see the appeal of not having a GC in a language like that. If it doesn't compete with C/C++ for performance and low level support then not having a GC is no longer an advantage.

That said Koka still remains very cool for the effect system though, and I would really like to see it in a mainstream language!