hi jonathan, i will let sebastian comment on this more directly (and accurately) but last i recall webpd used sink.js and he definitely wanted to transition to web audio fully. looks like he's well into the process of this transition based on the github page...
i would personally not worry about making it work with Mozilla's Audio Data API. it has basically been abandoned by Mozilla in favor of Web Audio, although it's a bit of a slow transition. Web audio is already available in their Aurora beta browser, though i believe the code has to enable it first. by next year this time i believe Firefox will fully transition to Web Audio and everyone will be on the same page.
scott