I went to the range today, shot a Uberti Flattop Target SAA in .44-40 with 7 1/2" barrel and a Gregorelli & Uberti 1851 Navy .36 caliber. I used moderate loads in the Flattop with a 200 grain bullet lubed with beeswax/lamb tallow and about 27 grains of Goex 2F plus a small amount of filler. In the 1851 Navy I used about 20 grains of Goex 3F and a .375 roundball, no filler, no lube.
The point of this post is to contrast what it's like to shoot a black powder cartridge revolver compared to a black powder cap n' ball revolver. The Flattop was fairly mild but in comparision the Navy was super, super mild. Even though 20 grains is kind of a stout load for the Navy, or if not stout, I don't think it would be considered a light load. The Navy is just way easier to control. I tend to think this is why Wild Bill Hickok kept his pair of '51's well into the cartridge era. I could see someone becoming so familiar with the '51 that they don't want to change, even if more technologically advanced cartridge guns are readily available.