How much does the data change on a daily basis?

a differential copy might be your best strategy... do you need it archived in a snapshot? (i.e. able to return all data to a checkpoint in time)

Attix5 is able to do both of these... not sure on providers in Germany but I am sure they must have a representative there.
This is available in both hosted and installed flavours... The smallest licenced protected data is 500Gb. They licence on amount of data to be protected not he space it takes up in the archive system

We were protecting 2Tb, remotely backing up offices all over Europe. For a sales office in Italy we were protecting 200Gb with a daily delta of around 30Gb but transferring < 20Mb over the network (many of the files were PSTs and we used block level differential)