Hi David,
I can only offer a partial answer. My DA-RMAs did not have the poly crossovers, so I did the poly and the V2 at the same time.
The focus and soundstage became much more open and clear, with greater transparency. It seemed to remove a lot of obfuscation in the spaces between instruments.
My friend Jon has poly Athenas that he upgraded to V2. The differences were similar, I think, but not to the same degree as mine. Others have written similar assessments. So maybe 40% of the improvement is the poly, 60% V2?