Ulitmately, the user is responsible for their own security. You cannot entrust this with the service operators.
There is no way of proving that the software actually running on SN servers is the one that's on GitHub, and not a forked version that FBI made them run. (You can only theoretically verify the client yourself.)
Does it make sense for you guys to have a canary page? @ek@k00b
If you want to use multiple identities and hide that fact from the service, use a different Tor/VPN exit node for each. Use separate browsers or browser profiles too, to avoid fingerprinting.
ALWAYS assume someone (could be your ISP) logs your IP and the fact that you connected to this or that website.
Be conscious of "social fingerprinting" - activity hours, writing style, tipping patterns.
Ulitmately, the user is responsible for their own security. You cannot entrust this with the service operators.