By not matching do you mean that Rx.Net doesn't have equivalent concepts of different types of thread pools to send work to?

I think the part of Rx.Net that we want to mirror is the interfaces and mechanism for getting different implementations of schedulers - but I think Java can and will have more implementation options, particularly via contrib modules. For example I fully expect to have a module that implements schedulers on top of Akka Actors for environment that use Akka.