Ok, I understand now that the overhead is intrinsic and is no "problem" of Espionage. Thanks for the clarification.
The past days I tested ZumoDrive, SugarSync and Dropbox. It seems that only Dropbox is working properly with Espionage. Here is the test "scenario": I created a test folder with a test file ("Hello world"), encrypted and uploaded it to the three services. I then unlocked the folder and changed the text file ("Hello World" --> "Hello Planet"). Afterwards I tested how long each of the three services needed to upload the changes from the Espionage's built-in backup feature. Note: I have a low bandwith, everything takes quite a while here...
Dropbox only needed a minute or so.
Zumodrive and Sugarsync needed over an hour...
My conclusion: There are cloud storage solutions which can't' just upload only the changed parts of a file or folder. They always upload everything all over again, which renders them unusable with Espionage. The only service I found which worked nicely was Dropbox. They also explain this behavior in their help section (https://www.dropbox.com/help/8). I guess Dropbox suits my requirements the most.
Christian
The past days I tested ZumoDrive, SugarSync and Dropbox. It seems that only Dropbox is working properly with Espionage. Here is the test "scenario": I created a test folder with a test file ("Hello world"), encrypted and uploaded it to the three services. I then unlocked the folder and changed the text file ("Hello World" --> "Hello Planet"). Afterwards I tested how long each of the three services needed to upload the changes from the Espionage's built-in backup feature. Note: I have a low bandwith, everything takes quite a while here...
Dropbox only needed a minute or so.
Zumodrive and Sugarsync needed over an hour...
My conclusion: There are cloud storage solutions which can't' just upload only the changed parts of a file or folder. They always upload everything all over again, which renders them unusable with Espionage. The only service I found which worked nicely was Dropbox. They also explain this behavior in their help section (https://www.dropbox.com/help/8). I guess Dropbox suits my requirements the most.
Christian