Regarding the recent analysis on Monero transaction traceability published and co-authored by Zcash advisor, Andrew Miller, we're happy to see continued research efforts on security/privacy in various cryptocurrencies. The Zcash Company had no involvement with the research (either in contribution or sponsorship) but being a science-driven team, we fully support the efforts by researchers (whether affiliated or not) in producing publicly available, well-backed science. Research like https://monerolink.com and the other paper released a few days later covering similar concepts (https://drive.google.com/file/d/0B7e8g-wJId8md3FYUGF0TlB5NjQ/view) are critical for users to better understand the risks when becoming involved in these experimental technologies.
Even though we attempt to be very clear when educating users about the risks of Zcash (such as the differences in purpose of transparent vs shielded addresses), similar analysis on the Zcash blockchain (even in it's infancy) is welcome and encouraged! Protecting users from risks to life and liberty and communicating those concepts from different perspectives should be priority, especially for technologies which focus on user privacy and security.
Having multiple approaches to blockchain privacy is beneficial for the entire ecosystem. In fact, having considered the vulnerabilities in mixing & ringsig approaches to blockchain analysis is the reason why @zooko started Zcash in the first place! Had there been proof that these types of systems are safe for users, Zcash would not be here today.
Providing good security and privacy in open networks is a complex problem, and we need all the help we can get. Our company is a science-based company, and we strongly encourage scientific research — whether studying the Zcash technology or other technologies — which exposes vulnerabilities so that we as a community can learn, and can better protect users.
In the end, the goal of Zcash is to be general-purpose Internet money and privacy (and fungibility) is just one of the requirements for that.