IME, yes plants are better than no plants 9/10 times. Even if they are out of the display and into the sump.
1. They are faster at absorbing ammonia than the bio-media can convert into nitrate.
2. They provide oxygenation during the day
If you only want the first benefit; you can use emergent plants in the sump. The roots will absorb the ammonia faster than aquatic plants can use it. Or do both [aquatic and emergent].