Honestly, I think you're better off not using xxxduino or Arduxxx, but instead creating your own name. That way you create a brand and are known for your own products, rather than as a derivative of another project.
I do agree. I think that too many boards are called xxxduino and they are often not compatible with the arduino shields that I would have thought would be an absolute minimum to be called that.
Obviously calling it xxxduino gets people to relate it to arduino but I would avoid that and give it a new name...
I'd keep xxxDUINO for boards that are both logically and conceptually nearly entirely similar to Arduino. If you add significant functionality (ie for robotics) you might as well pick an entirely new name. For example, Freeduino and BoArduino are intentional and exact clones (more or les) of Arduino, while http://www.evilmadscientist.com/ has several projects that are compatible with the Arduino environment and bare names with no "ino" in them anywhere (Peggy2, Bulbdial, Meggy Jr...)
On the other hand, adding that -uino suffix does a nice job of instantly conveying an attempt at arduino compatibility, and aids web searchiblity. (Who named "Processing" and "Wiring" ?! HORRIBLE names to try to search for info. "Arduino" works MUCH better, and a non-word that isn't even Italian is probably better...)