Santamonica is sold on the turf scrubbers. He made a really nice one for his system. A good thread if you want to learn from his mistakes. He has done quite a bit of experimenting.
Once I get my fuge up I might add a small scrubber.
They do not take up much room and probably remove more nitrates per space occupied than a refugium.
They do sound like they are higher maintenance. Cleaning the gunk out every week vs talking a clump of chaeto out.
I don't know if I would put all my eggs in one basket but if maintained they look to be effective at removing nitrates and phosphates.
He thinks it can replace a skimmer. Not so sure about that.