I was a bit skeptical about the local disk usage with Git, as every Git clone is a full-fledged repository with complete history, and apparently Git stores entire snapshots and not the deltas.
Everyone seemed to be claiming that Git is quite efficient in terms of storage space required, and I also found the following statistic on the web
"The Mozilla CVS repository was 2.7GB, imported to Subversion it grew to 8.2GB. Under Git, it shrunk to 450MB. Given that a Mozilla checkout is around 350MB, its fairly nice to have the whole project history (from 1998) in only slightly more space."
But I was still a bit skeptical... :)
So I downloaded some of the JDT source from Eclipse Git repositories and compared the disk usage under Git with CVS. Here are the numbers. For these selected projects, Git on an average takes less than three times the space required by CVS. In my opinion this cost is nothing as compared to the benefits of having the entire history locally.