Pixhawk 2.1 non GNSS flying as good as paired with one?

Hardware Pixhawk 2
1

Hi.

I am about to pull the trigger on Pixhawk 2.1 minus GNSS but red somewhere that even when flying in non GPS mode coupled with Here GPS somehow you get a better results than without it connected at all. Is this true? What other sensors are there onboard GNSS module except satellite positioning?

2

It does have a compass inside. And belive me, you will want to use it.