Okay, something else must have been hitting my server hard drive. FTP speeds have now increased to 1.3 - 1.5 MB/s with the same CPU load SCP speeds and loads are the same.

Asus Transformer Prime, Power mode enabled. Using System tuner to monitor CPU usage. On my Ubuntu server, using openSSH server and vsftpd. Connecting to the server via local wifi network (802.11g) Downloading to the "built in" sd card (i.e. the non-removable 32GB or 64GB that comes with the device),...