Are you using this string?
4b00000001000000010000003f0000000100000002010c00d041030a0100000001010600001e0101060000017fff0400160000006200750069006c0074002d0069006e0000000500000001
I installed IONetworkingFamily like this, and my SuperDuper issues went away:
sudo cp ./IONetworkingFamily /System/Library/Extensions/IONetworkingFamily.kext/Contents/MacOS/IONetworkingFamily
sudo chown 0:0 /System/Library/Extensions/IONetworkingFamily.kext/Contents/MacOS/IONetworkingFamily
sudo rm /System/Library/Extensions.mkext
Of course, I'd rather have an EFI string as to me, that's much cleaner.