Kerberos FTP (Score 1)

I've never used it, or even looked at it, but perhaps something like a Kerberized FTP. You may want to try different encryption protocols for scp/ssh. SSH defaults to using IDEA for encryption, which is 64% of non-encryption speed. You can switch to Blowfish, which runs at 88% non-encryption speed. Just use the -c option with ssh/scp. And finally you can look at an unsecured file transfer, such as stock FTP, over IPSec. Check out FreeS/WAN if you are using Linux.