incremental dumps

Hi,
I want to store copies of our data on a remote machine as a security measure.
My first attempt was a full dump (which takes too long to upload)
followed by diffs between the pgdump files.
This provides readable / searchable versioned data (I could alway apply
the diffs on the remote machine and search the text file, without having
an instance of postgres running on that machine)

However, the diff files seem to be considerably larger than one would expect.
One obvious part of the problem is the fact that diff shows old and new text,
so e.g. changing the amount of stock for a product with a 1kB description
would generate at least 2kb of text in the diff file.

What would be a better approach?

Best regards
Wolfgang