.odt vs .fodt: which is most space effective for git repositories?

I performed following test:

Put 5 revision of small .odt to repository. I made small changes in every odt-document.

I commit similar data for .FODT. They are obtained by extracting corresponding revision of ODT and saving it to .FODT.

My results follow:

       before gc    after gc      
odt      260k         260k                
fodt     118k         38k        

Note, I measured size of .git directory where revision actually saved.

I did not accounted ODT/FODT-file itself because this does not give reasonable results.

I measured size of .git folder only.

ODT is very similar to zipped FODT and it is expected that FODT is much larger than ODT.

Since it may sense to estimate grows of Git history then ODT/FODT should be excluded when measuring size of Git, because they are stored directly one time only independently of history length. In long run history consumes most space, so to obtain more relevant measurements on simple test the documents itself in working directory should be NOT be accounted when estimating the size of repo.

Doing some quick-and-dirty testing, I put ten revisions of a tiny .odt file into a bare git repository, then put the same ten revisions of the document in .fodt format into a different bare repository. The resulting sizes of the repository:

       before gc    after gc      
odt      408k         188k                
fodt     399k         148k                

So .fodt offers a very slight saving in repository size, even though the .fodt file itself is 2.7 times bigger than the equivalent .odt file.