I had a pair of A. tomentosus in my 150. They definitely helped suppress the aptasia. Using livestock to treat aptasia will rarely fully eliminate it; removing the fish/shrimp will typically result in its return. I have a Copperband, Filefish, and pair of peppermints in my tank and haven't seen aptasia in my display for months.
They are also known to nip at corals, mostly LPS and softies.