Price , originality of package and condition are always the determining factors in a collectible firearm,
Doubt there will be a huge difference in accuracy on the range or even clamped in a ransom rest and
I seriously doubt a blindfolded shooter could tell a Model marked 27 from a pre war RM even though one has a longer action.

As for actions I have a 66-2 (NON P&R) that has a better trigger/action than any other S&W I own so depends on the gun itself and work done to it.