I recently had a 3-4TB data transfer for a client who are a publishing company in NY. They wanted to trasnfer all their files to a new server. I detailled how I did in another post, but what happend was that took couple of hours and during that time there were more files had been added to the system so I had to re sync them.
find files/ -mtime -10 | xargs tar -cvf ~/files_latest.tar --no-recursion
-mtime -10 means find the files that are modified within last 10 days. You can specify +10 which means find files that are older thatn 10 days. Look at the find manual for more information.