[martinkallstrom]

Even if you trust that your own computer or server is more secure than Greplin's servers, your communication with others will be indexed on instances belonging to the people you communicate with as well.

So the question even for the seasoned computer security expert that want to use a distributed Greplin variant is: Do you trust your friends and colleagues to have better security on their home or work computers than Greplin can achieve with dedicated work?

With a distributed system it would still be a non-trivial task to protect against a dedicated worm or trojan that infest the network and traces paths to other Greplin users after stealing all the data from each instance.

Since the data is social and each document in many cases concerns more than one person, it might actually be a less complicated task to achieve sufficient security in a central location.