any qualified opinions here on tresorit? i'm using them now for about three years and the service is alright and reliable afaiac. supposedly they don't have the private key. that makes using it sometimes a little slow compared to other options. but i decided to go with them after reading numerous horror stories about dropbox et al.
Was Tarsnap evaluated? Those behind it are well known and the construction is simple and explained clearly. My general rule: never make technology recommendations without throughly vetting/testing multiple candidates and digging deep into support, the company, and demoing close to intended use.