The way I'm thinking, the open top Colts have seen very extensive use back in the day. If they were easy to break, they wouldn't have used the same system for 40-ish years. Structurally the open top Colts seem very sound for shooting any BP load, provided all the components are fitted correctly. There's not much more steel which holds the Remington together. I don't think "structural strength" is a good reason to shy away from Colt designs, but I would avoid brass framed anything.
I have a (steel frame) Remingon 1858 I'm happy with, but I'll probably grab one of the open top Colts as well down the line.
For a brass frame, go with light loads with round ball; or alternatively just accept that the gun will go loose at some point and that it will have to be replaced and shoot whatever you fancy. The only guy I know who bought a brass frame did just that. They're not all that expensive, in the end, and once you get hooked on the sport you'll persuade yourself to buy another very easily
I have a (steel frame) Remingon 1858 I'm happy with, but I'll probably grab one of the open top Colts as well down the line.
For a brass frame, go with light loads with round ball; or alternatively just accept that the gun will go loose at some point and that it will have to be replaced and shoot whatever you fancy. The only guy I know who bought a brass frame did just that. They're not all that expensive, in the end, and once you get hooked on the sport you'll persuade yourself to buy another very easily