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I doubt it would be useful as the Roadster is very unconventional. There are no O2 sensors or the host of normal measurements. I think Tom Saxton sells an ODB that is specifically designed for the Roadster. Check out more of the Roadster threads.
The myEV project is using the diag port (not obdii) on both roadster and model s. IMHO, there is little point connecting to obdii port in roadster. 1MHz bus is not supported by most tools, and there is little there anyway.