I set up some test jobs, these are the results before cache write enable (over gigabit LAN), the last job (copying from one folder to another on the VM) is just shocking:

Job: Test_Copy0 - My home directory NAS to VM
Run Time: 11/03/2012 11:24:57 to 11/03/2012 11:30:53 (Duration: 5:56)
Status: Completed Successfully
Files Processed: 4,522
Files Copied: 4,519
Folders Processed: 346
Bytes Copied: 1,863,435,115
Bytes per Second: 5,229,785

Job: Test_Copy1 - Zip of my home directory NAS to VM
Run Time: 11/03/2012 11:30:53 to 11/03/2012 11:32:33 (Duration: 1:41)
Status: Completed Successfully
Files Processed: 1
Files Copied: 1
Folders Processed: 1
Bytes Copied: 1,523,321,591
Bytes per Second: 15,145,674

Job: Test_Copy2 - Zip of my home directory VM to VM
Run Time: 11/03/2012 11:32:33 to 11/03/2012 11:38:46 (Duration: 6:12)
Status: Completed Successfully
Files Processed: 1
Files Copied: 1
Folders Processed: 1
Bytes Copied: 1,523,321,591
Bytes per Second: 4,092,717