I've read on several discussions here and on SO that DVCS repositories use about the same or less space than their centralised counter-parts. I may have missed it, but I haven't found a good explanation of why that is. Anyone know?
From my own experience, the following statements are all true:
If you compare the checkout location (which is a repository in itself with Git), the story is totally different:
If you compare the amount of bytes you have to down- or upload, it is different again.
So at the end, you compare apples with oranges, and depending on what you want to do with Subversion or Git, the result may be different.
@jk asked about complete copies or binary diffs, and I could not answer that question. I asked Matthew McCullough which gave a Git workshop lately at Jax 2012 (which I visited). He has taken the time (thank's a lot to him) to explain with a detailed gist the inner working of Git. So yes, there is a compression working there (and I will do an experiment with a microsoft office file as well and will compare that with his gist), but not, the compression is done on the whole file. Citing from his gist: