Of the listed units, only the HR21 can be a source. It can serve up an MRV stream to either one (but not both at the same time) of the HR21s.What is the best path for me to allow for the dvr content to be streamed to the other rooms in my home.
The D12 receivers are not MRV capable.
The HR24 will be able to play streams from the HR21 or serve up the other H series boxes (again, not at the same time).