Bernt,
It would actually help us if you could provide details on the products in question. One of the main goals of this site is to help serve as a clearinghouse for RDM compatability information and to help the Manufacturers work together to address any issues.
There is a lot of product out there that was built to draft versions of RDM. We intentionally decided to not choose the official RDM Start Code until after the Standard was finished. This has helped keep the draft versions from creating problems with the final version of the Standard.
There are no RDM police to control when someone states something is "RDM" or not.
What Start Code did you see the traffic under? 0xF0 was the prototyping Start Code we used in all the draft documents. The list of registered Start Codes can be found at:
http://www.esta.org/tsp/working_grou...rnateCodes.php
Again, if you can provide specifics on the gear, then I might already have information on what protocol or version of RDM is being used.