Saw his comment and I’m looking forward to the results 
Tom has some nicer toys to play with than many of us 
For a simple setup like the one you describe I wouldn’t use it - maybe ZIL/L2ARC if the numbers/workload adds up.
For my personal setup I’ve got an Optane SLOG in front of a 6disk raidz2, because I need sync writes (photos so don’t want to risk anything). I don’t need L2ARC right now, but persistence looks promising, so might bump the server to max RAM and add L2ARC 
The major thing to remember with special-vdevs are the need for redundancy. Loose the metadata vdev, and your pool is toast.
The setup I’m considering using special-vdevs for is one where there’s a lot of files pr. directory and a lot of updating of these. The pool will be 3x 6disk raidz2. Persistent L2ARC might also be able to help a lot in such a scenario.