I did a WHOLE lot of repair work and trigger jobs on Original and Repro Smith Carbines between the early 1980's and my last National NSSA shoot in 2005. Matter of fact for many years, I was the only one willing to do a trigger job on a Smith during the Nationals, because it is so involved and takes so much time to do. So while I highly regard the Original Smith Carbines, I would strongly advise against the purchase of even a repro, unless you get into NSSA shooting.
I also did trigger jobs and other work on other UnCivil War period guns used in NSSA competition. I only accepted a Shiloh Sharps one time for a trigger job and that wound up being a Royal PITA !!! The half cock notch was broken off, so it required a replacement tumbler. I went all over the Sutler area, but nobody carried spare parts for the Shiloh. Yeah, I was told original Sharps tumblers would interchange, but found out that was NOT true. I was able to fit an original tumbler, but it took way too much handwork and I knew what I was doing.
If you wish to buy a Sharps repro or some other period breech loading rifle, I would strongly recommend you get an extra tumbler and sear when you buy it, if you wish to compete with it and shoot it a lot. I say this from having to hunt down repair parts at the NSSA Nationals, which is normally the BEST place to find repair parts on short notice. Too many times I went all over Sutlers' Row over the years and while Sutlers/Dealers had parts back in their shops or places of business, what was needed was not available even there.
Gus