The "plowhandle" type grips on Single actions were designed for one handed use. Particularly when mounted on a horse. It was assumed your other hand would be busy with the reins or possibly a saber. (or another gun if you're Rooster Cogburn
)
It works pretty well, until you reach beyond the recoil level of the .45 Colt. It positively was meant to "roll" in your hand, Putting the hammer spur closer to your thumb for cocking "on the way back down".
But if you shoot them like proper single-action revolvers, the standard style grips will be even better - and the rubber terrible.
Good or terrible is a personal matter, I think. For me, the rubber pachmayr grips work better, and I much prefer them to the smaller stock wood, on anything with significant recoil.
And I require them on SA guns with heavy recoil. First, they're bigger, which fits MY hand better, and they fill in behind the trigger guard, which keeps my middle finger from being painfully bashed shooting heavy loads.
They do roll in MY hand, but a bit less than wood, turning what could be 110 degree muzzle rise into 70-80 degrees or so, which still allows me to thumb cock the gun one handed without any difficulty.
Additionally, I don't know if the rubber actually absorbs any recoil, but it feels like it does. I put rubber on my DA revolvers for the same reason.
My Blackhawks and Super Blackhawk all wear pachmayr grips. 6.5" barrel on the .357, 7.5" on the .44 and .45 Colts. My Super Single Six wears stock Ruger wood. No problem on that gun. But, on heavier recoiling guns, I want the size and feel of the rubber I have on them.
I don't care if someone else thinks they are ugly, or if they don't like the feel, on their gun, its their choice. On mine I want them to feel and work the best they can in MY hand, and for ME, wood is worse than rubber.
The Bisley grip shape doesn't roll in the hand like the plowhandle, it was designed for (dismounted) target shooting. The fact that many people find it handles heavy recoil better than the plowhandle shape is serendipity. At the time of its design, the heaviest recoil was the .45 Colt throwing a 250gr up to about 900fps or so.
If you expect to hold on to a SA revolver "rock solid" the way you should a DA for fast shooting, you're not going to be very happy with the SA. The very shape of the gun works against that. Let it recoil, and haul it back down to line up for the next shot. It's a repeater, not a machinegun.