I figured you would want the power inlet you linked for two reasons: fuse protection if something shorts out and removable power cord.
You definitely don't want to use the power inlet to kill power without shutting down Windows first.
Whether you need the smart strip depends on your desired power on/off sequence.
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If you don't use the smart strip, you can use the inlet switch to apply main power to several outlets (monitor, computer, etc.), and press a button to turn the computer power supply on.
To power-down this setup, press the computer power button to tell the computer to shut down or some front end programs can send a shutdown command when you exit the program.
Once the shutdown is complete, switch off the inlet power to shut off the monitor.
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The smart strip can remove the two steps in the process involving the inlet switch.
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Your call on whether it's worth the space and spending the money on the smart strip to avoid the inconvenience of waiting a few extra seconds for the system to power down before you cut off the inlet power.
Personally, I'd be more inclined to use a smart strip in a full-size cab where reaching a main inlet switch on the back would be far more difficult than reaching the same switch on a bartop build. YMMV.
Scott