I was fortunate enough to get a pair of author sample ASM .44 Colt conversions when they came out around 2000 or so. I loved them, but one had a periodic timing issue (not uncommon with ASMs). They were graceful, and closer to originals than the later Uberti versions - except no stepped cylinder.
Alas, they went the way of most author samples, on to the next evaluator. Since then I have had both Uberti Conversions and Open Tops in the mid-2000s. I think that the Type I Richards, with the 1860 barrel configuration are the coolest of the breed as far as looks. .44 Colt/.44 Ruussian/.44 Special makes them versatile as far as loads go. The Open tops, however, are the real charmers...
The 1872 Open Top, at least to me, is graceful and sleek, points nimbly and true, and tend to shoot horizontally in line with the POA, since the front and rear sights are on the barrel. For the Henry or 1866 shooter, they are a natural since in reality, both the rifle and pistol used the same ammo. Having both in .45 allows me to use my 200 grain Schofield load, duplicating the .44 Flat rimfire. If I was a lawman back then in the 1860s (as I was in real life now), I would have had a Henry rifle without a doubt. When the 1872 Open Top hit the market, I would have bought a brace of them to go with my Henry.
The .44 Henry Flat rimfire , with its 200 grain bullet pushed by 28 grains of powder, gave about 1150 fps from the rifle and 800 or so fps from a pistol. An 1872 revolver would give about the same energy as a standard velocity factory 44 Special today (about 300 ft lbs). From the rifle, it gave about 600 ft lbs at the muzzle and around 425 ft lbs at 100 yards. Even at 100 yards from the rifle, it gave more ME than a 200 grain .45 ACP at the muzzle. People hunt deer and pigs with Marlin .357 mag Marlins, and they are about the same as the Henry in terminal performance.
The .44 rimfire was not a powerhouse, but it was no slacker either. In a revolver, it duplicated or bettered the contemporary .44 Martin (Colt or Remington) cartridge in a pistol, and was more potent than the other .44s - the .44 Russian &.44 American. It even gave the .45 Schofield a run for its money. The well regarded Remington .46 French rimfire (for their first cartridge conversion of the Army Models), had a 227 grain, .456" diameter bullet, powered by only 20 grains BP, 30% less powder than the .44 Henry
Yep, if I was an 1870 Lawman, I would have felt well heeled with a pair of Open Tops and a Henry. I would head out into the Sierras with a couple hundred rounds in my saddle bags, and never feel out-gunned.