Yes, this is a great way to expand capacity and performance. If two or more Tempo-X, X4+4, X8, X4i, X4P, E4i, or E4P cards are installed to the same machine they must all have the same firmware version to avoid conflicts.
Althought the TSATA supports booting from an attached drive, it does not support target disk mode when booting from an attached drive. Try connecting the two computers via ethernet to exchange files.