RE: Ransom Rests...
Excellent devices that helps measure the mechanical accuracy of a handgun. Polymer guns are not compatible with Ransom Rests -- too much give in their frames.
That said, I suspect there are polymer-framed guns that are very accurate, as accuracy -- if you're using the sights -- is dependent on consistent slide/barrel lockup and not slide to frame lockup, and polymer guns are no different than steel-framed gun in that regard.
Most guns, steel or polymer, are capable of more accuracy than the folks shooting them -- and this discussion tends to be a bit like clerics arguing about how many angels can dance on the point of a pin... Lots of opinions but hardly any evidence, proofs, or examples.