I admit I never paid attention to Remington grips before.  And now that I have both Piettas and Ubertis, I still didn't notice until I put them side by side.  I had to look at pictures of a few originals to realize the Uberti is pretty close but the Pietta is not.  A little longer, less flare in back, different curve.  It's like the bisley of Remington    Since I'll be shooting them two handed it won't matter much, but I wonder if it makes much difference in duelist shooting?  As some have noticed as well, the Pietta frame is thicker between the cylinder and grip frame, which makes it harder for me to reach the hammer one-handed.

Well well well!  Another big difference that just came to light is the hammer stroke.  The Uberti conversion is like a short-stroke hammer compared to the converted Pietta.  I didn't notice at first because my main match guns had been R-M conversions and those are a short stroke compared to SAA type guns.  But then when I started working on the Piettas it became apparent.  I can't say about the Uberti percussion Remingtons, though I suspect those may be a longer stroke.

Forgot to post the picture.  This shows the difference in hammer strokes.

  Uberti is close to original, at least mine are....though the Pietta is a work horse.

  Well Now

Were I gonna be stuck shooting Remingtons (I ain't), based on the grip shape, my choice would be the Pietta.  That little flair at the bottom of the Uberti would tend to cause me to shoot just a bit low.