I shoot .454s in all my Italian repro .44s: a couple recent* production Pietta Remingtons, a Euroarms Remington, and a Euroarms Rogers & Spencer. Everything else being equal, the .454 balls will give a longer bearing surface in the chambers and barrel which should result in a better seal and more lead for the rifling to grip for better accuracy. They remain easy to seat using the gun's loading lever.
The longer bearing surface in theory sounds quite reasonable for better accuracy and I would not dispute that you are correct in some cases.
It really depends on the individual revolver.
I have always used .451" round balls in both my Remingtons because that is what was always previously recommended. The accuracy in both of my revolvers was and is very good, and I never saw any reason to change to the .454" size.
Logic dictates that a larger diameter ball takes more effort to swage down to the chamber diameter when loading, and videos that I have watched suggest to me that this is the case. But, I confess that I have not tried using .454" round balls so I can't claim to have personally compared the two.
And comparisons are relative, I suppose. What one person thinks is easy, another might not.
And like I said, I suppose that it depends on the individual revolver. If a larger ball is accurate and a smaller one is not, then you will use the larger ball.
With solid frame revolvers, It really makes little difference if more loading pressure is a needed.
But, I think that open top revolvers are another matter. These are weak by comparison to a solid frame. The loading process puts a lot of stress on the wedge and wedge slot, and I would prefer to use the smaller ball size if it gives good accuracy.
However, if a larger ball is needed for accuracy for .36 caliber revolvers, as you say, what choice do you have but to use them?
Any thoughts on using patched round balls in cap & ball revolvers?