Foothill Corals your right, the smaller size in theory should work better because it will provide more surface area per sq ft for bacteria to live in. The push for larger size was only because of detritus build up, easier to clean, etc. I got a 200 gallon, with about 250 gallons total volume if you include sump and refugium. How many liters should I go with?
I would start with 3 or 4 liters and see were that gets you six months from now and adjust the quantity as needed.