It is great to read that security is your highest priority.
For me, as a customer, it is crucial to know that btsync 1) does what it is supposed to do, and 2) never does something it is not supposed to do. We can do extensive testing on the first topic, but not on the second topic. Does btsync contain backdoors? Will it leak my precious data to some foreign server? We don't now, and we cannot know.
Security is our highest priority as well. Are you going to publish reports of rigorous third-party security audits that address these concerns? Reports that include the checksums and/or GPG signat