My problem with any "Dead man switch" is the fact that none of these services seem to survive. Also, can you please write somewhere on the website what's your privacy policy? Is everything encrypted? if so, with what? By it's nature this kind of service will hold very sensitive information.
As with any service you should assume that nothing is encrypted (even though it is) and follow other articles that I've written about how to securely maintain private information when using third party services.