Like stealth, I don't have the background to really understand the ring-signatures ShadowCash uses; I was contacted by ShadowCash to do an audit and deferred it to a cryptographer I know. They said the math looked to be a clone of Monero, done on top of Bitcoin. They were however potentially interested in doing an audit of the ring signatures idea to get a better idea of what kind of privacy it really gives people in practice - we'll see if they have the time to work on that further in the near future.

Best not to say more publicly than that given I just haven't done the research to really know.