The Piettia "tail" is the most often disputed error they made. The taik is too sharp and as was said, "makes thee revolver shoot higher than it already does!
I reshaped the grips on a '51 .44 caliber "standard" Navy model and just rounding that tail away made all the difference in the world! I touched-up the frot grip base a tiny bit to hasten getting my little finger underneath it.
Still the "fuller" Peacemaker grip is even better on the hand and it turns the London '51 into a pleasure to hold. The Pecemaker also has a filled-in section at the front of the grip assembly whch further aids ones "hold"
I haven't actually held a Piettia but the grip looks exactlly like my Uberti's and should be just as good.
My Piettia mod assists my hold but really dosen;t exactlly mimic the Peacemaker style. What makes the Uberti so different is the smoothness of oleration that it has The action feels like a custom job! So smooth and light!
Given the quality differences between the two brands, I'd go with the Uberti if at all possible.