I'd use it on the nano. Go for a setting that is pleasing to the eye. Play around with the settings and see what you like. If you've got any corals with long tentacles it really makes them look great when they get caught up in the waves.
What it does for the corals and tank in general is provide varied currents. That helps keep dead spots down and helps to prevent debris from settling on corals. This is less important to some corals as they are capable of handling the debris that collects on them.
It probably isn't a piece of equipment that should be considered critical, but if you've got it use it. They can be a little too pricey for what they add, but they are beneficial.
