I always thought the Edirol Hypercanvas was the same as the TTS1 and the sounds were edirol/roland
Having owned a few Roland devices I can assure you the GM sound set is different on each.
Each Soundcanvas model, and everything after has differing sounds.
My Early SC was different than the RAP-10, which was different than one Roland synth to the next.
They have all been pretty good, but none exactly like the other.
FWIW, the MS default GM sound set that the WT synth uses is also from Roland, just really compressed, so pretty lo-fi and not updated in years.