I have a heavily planted refugium with RCS and neon tetras. The area for the fish and plants takes up about half a 55 gallon tank. The water is not quite to the top, so call it 20 gallons.
The neons and the adults ignore each other. I know the neons go after babies, because I've seen it. However, it's rare. Most of the time, there are babies all over the biofilm on the walls, and the tetras ignore them. But, they definitely eat some.
I've read of others who have had a terrible time. I think lots of cover and fish personality are both big factors.