Just for your info.
We have a bidirectional splitter that is RDM compatible, but which is a non-proxy splitter. So no intelligence but just the right timing to provide correct turn around of the bus.
At the time we tested it with several bidirectional units, DR1 was one of them.
Have a look at these units:
http://www.luminex.be/products_overview.php?cat=0
http://www.luminex.be/products_details.php?cat=0∏=0100010&display=description
http://www.luminex.be/products_details.php?cat=0∏=0100006&display=description
Regards