Judging by the pictures on Uberti's site, the 44 Russian model may have the correct relation between the cylinder gap and the cylinder pin for black powder shooters. The rest have longer cylinders that leave the cylinder gap directly over the base pin, with no bushing or other extension coming out from the cylinder to protect it from fouling. Some have also complained that the cylinder gap is too tight on the Uberti copies, but a gunsmith can fix that. Reworking the relation between the cylinder and the barrel gap looks like a more involved project, and one likely to add more than a few dollars to the gun's cost. You could also load one of the black powder subs that has greatly reduced fouling, which should give you no more trouble than smokeless loads. I like the fire and stink of real black powder, myself, but I could see using a sub if a particular gun required it to run well.
If you come across one of the old Armi San Marco top breaks, you probably don't want it. The book Gunsmithing Guns of the Old West explains why you don't want one. There are two original top breaks for sale on gunbroker.com, last I saw, and they cost the same as the modern Uberti copies.
Finally, some folks don't find the break tops to be very ergonomic, compared to other 19th century arms. You're the only one that can answer that, but you should certainly attempt to try before you buy, if you know anyone with a top break.
