The PL3507 is widely known for a weak FireWire implementation and sometimes extremely bad firmware. USB is supposed to work better on this though.
As far as sbp2 is concerned, failures to connect are perhaps fixed upstream. There was a regression in sbp2 concerning some PL3507 in Linux 2.6.16...2.6.16.19 inclusive. -- usb-mass storage disk isn't recognized the right way https://launchpad.net/bugs/36619 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
