I have been testing Openfiler 2.3 iSCSI as a Backup Destination for Symantec CPS 12.5 using Microsoft software iSCSI initiator as the connector. It is working great! I am using Cisco Gigabit switchports with jumbo frames enabled and the performance seems to be fine. Getting ready to add some additional servers to really test the load.
Key Point: in the MS iSCSI config, MAKE SURE the auto-connect on reboot box is checked.