The 1851 is the best handling cap gun of all time.
Most folks will tell you that it points better than any other -- like an extension of your arm.
They may quibble about the better aspects of a 44 for defending yourself, but as far as pointability is concerned, the 1851 is the hands-down winner.
The 1861 is very similar.
The repro-makers use the same frame & cylinder, only the barrel shape changes.
Most folks think the 1861 is prettier, but they shoot about the same.
Wild Bill carried a brace of 1851s.
The Remington is a fine revolver, but has several issues.
Because of the lack of a bushing on the cylinder, a remmie sprays the cylinder pin with fouling every time it is shot. After a few shots, it becomes harder to cock.
Many folks (including me) find that there is too little room between the rear of the trigger guard & the grip frame, so the knuckle on my middle finger takes a beating from shooting a remmie. I couldn't shoot them for a long time. Then I had the bright idea of relieving the TG & gripframe to make more room. It worked.
The arc of the hammer as it is cocked is longer, so in a match, your cocking thumb can get stressed more than with a colt. That may be neither here nor there for you.
With a Colt, if you desire larger grips on your 1851, say, if you have large hands, you can swap the grips out for the larger Army grips. Me? I like the smaller Navy grips, so even my 1860 Army (.44) revolvers wear Navy grips.
If yer curious, Sam Colt chose the smaller Navy grips for the Colt 1873 revolver.
Weight = about the same
recoil = Remmie has more because of heavier ball & more powder
Ease of loading is tilted towards the Remmie as you can load on the gun or easily remove the cylinder and use a cylinder loader like the Powder Inc or Tower of Power.
However, a properly fitted Colt wedge comes out with thumb pressure & it is easily loaded with a cylinder loader as well. Although, you end up with 3 pieces laying on the table instead of two. And, the wedge must be properly fitted, which takes a bit of effort.
In the final analysis, you should shoot both & see which one you like better.
Many folks are rabid about one or the other.
I like Remmies, and every time I see Pale Rider, I want to buy more, but the bottom line is 95% of the time, I pack the range bag with Colts.
--Dawg