Operating System Requirements: Mac OS X 10.4+, Mac OS X Server 10.4+ Description: This software enables the use of Tempo SATA E4P and Tempo SATA Pro ExpressCard/34 (3Gb model) in Mac Pro and MacBook Pro, respectively.
Under macOS, If the driver doesn't load, you may need to go to System Preferences...Security & Privacy panel...General tab, and manually authorize the Sonnet driver and restart.
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.