I adjust mine so my moss has a gentle sway to it and water gets evenly moved around the tank. They seem to like swimming against the flow and popping up and down, but its nowhere near strong enough to keep them from making progress or trying to swim against but losing the battle.
I've had them breeding in a 2.5 gallon tank with the smallest internal power filter I could find. Its basically a sponge filter with a powered motor on it. Its completely quite and moves about 10 gallon. They also do fine in my 15 gallon with a standard HOB on the back.
I have an Edge and a chi, both with hob filters. I prefer to have them on about half flow. My neos will brave the current and climb up the outflow and pick around on it. Strong current isn't the most shrimp friendly, but moderate is fine. Main thing is to have a fine mesh or sponge guard/pre-filter on the intake to keep babies from getting sucked in.