Quick update here. First off it's "Transwaves" and second here's a small demo of SQ2 that sounds like its using a PWM transwave: http://homepage.mac.com/synth_seal/files/j_sq2/sq2_polyphony.mp3

Not exactly hard sync I know but at least there's a convincing PWM. Check out the entire website actually since there are some more demos of different transwaves.

cheers,