Excellent article. PIVX is actually moving over to Zerocoin privacy protocol for most of the reasons highlighted. In fact we've already implemented it successfully on the testnet and will be pushing for full implementation within weeks, once we've finalised setup parameters and GUI. The fundamentals of anonymity are very much the same but our implementation will come with some advancements over most current implementation increasing efficiency & usability. All source code will be open so all projects can audit and use the improvements we've made. We do disagree that leaked setup credentials can lead to forged coins, but agree it can cause zpiv origins to be calculated thus rendering the anonymity useless. However it's not a problem worth worrying about for any of the coins mentioned as they're all well organised and setup. Great to see so much progress in the realm.
RE: An overview of blockchain privacy mechanisms and how Zerocoin in Zcoin $XZC (not Zcash) stacks up