Can't comment on Vp180 but the drivers on the VP160 and an M60 are identical.
I have the 160 with M80s and the 160 is phenomenal, No trouble at all with my M80s. Even of axis at low volume dialogue is crystal clear.
Have read in other forums the driver configuration of the VP160 has best of axis response.
But with the size and beauty of the VP180 I would think the off axis sound would be pretty close.

How does the off axis on the VP180 perform???