I've owned both and shot them in matches.
Every time I grabbed the Bisley in a match, my purchase was different than before. There is so much real estate on that grip that it can be apprehended in many different ways. Needless to say, this does not help one's shooting!
The plow handle, on the other hand, offers a more consistent hand to gun mating because there is simply less area to move around on.
I much prefer the plow handled guns and never could run the Bisley's consistently.
However, several one-handed shooters (duelists and gunfighters) use the Bisley frame because when the gun moves under recoil, it brings the hammer closer to the thumb for cocking. But, I've noticed several long-time gunfighters switching over to plow handles the past year since SASS changed the rule on hammer substitutions in guns. Apparently, the hammer of the Bisley has been the Huckleberry all along. Not the frame.
It would be much more difficult to develop a consistent purchase on a Bisley frame than on the plow handle. That was my experience, anyway. I got rid of mine.