Can I move data from old to new Time Capsule through USB?
I'd suggest using rsync from the terminal. It may still be slow, however:


It should be faster than finder.
You can stop the transfer any time. It will resume from where you left the next time you issue the same command.


So, it should both reduce required time and also make it possible to stop it and resume if you actually need to use your computer.

sudo rsync -avPh --delete-after /path/to/original/gromit.sparsebundle/ /path/to/copy/of/gromit.sparsebundle/


Explanation:


-a: Archive (be recursive, preserve timestamps ownership etc).
-v: Verbose.
-P: Show progress and real-time transfer rate.
-h: Human readable output.
--delete-after: At the end of copying remove any files at the destination that don't exist at the source. This gives you the freedom to continue making backups on your old time capsule without worrying about excessive files being copied to the new one.


Important: The trailing slashes in the two paths are important! If omitted a new dir may be created when you resume the sync (i.e. /path/to/copy/of/gromit.sparsebundle/gromit.sparsebundle).

Also note that the transfer rate displayed with the -P parameter is not accurate when small files (a few KB) are transfered.