I don't know how the reproductions are- never shot one, never even saw one in person. I've read some good things about them. Supposedly the Rogers and Spencer is a good solid piece.
Its history is a bit odd. What I read about it, I read long ago, so this may not be entirely correct.
Rogers and Spencer, of Utica, New York iirc, were manufacturing a number of revolvers during the Civil War. These included an odd-looking double action, the Pettingill, mainly notable because its barrel and ramming lever look identical to the one on the Rogers and Spence revolver.
As i remember the story, they were investigated for fraud and lost their contracts, although it turned out they weren't guilty of anything. Then the head honcho for arms, who had been involved in investigating them, signed another contract with them for 5000 improved revolvers. The R&S was the result- a much more conventional revolver than the earlier designs the company made. The book I read suggested this was done to try to recompense R&S for what they'd lost when their earlier contracts were canceled, more or less wrongfully.
Be that as it may, Rogers and Spencer made the 5000 revolvers and delivered them. And then the Civil War ended, before a single one was ever issued. The whole lot went into storage. However, since they were actually purchased by the government and delivered during the Civil War, they are allowed in skirmishes by the North-South Skirmish Association.
The entire 5000 revolvers went into storage. They stayed in some warehouse or other for decades, then got sold off (still unissued and unused) as surplus. Surplus dealers sold them to the public. Since they were never used in (official) battle, a fair number of them even today are in excellent shape, with very little wear and tear.
There aren't many around because the Remingtons were made in huge numbers and used throughout the Civil War and afterward; the R&S in small numbers, and never issued to the army at all. But they were a good, solid design. If the Union forces had been issued R&S instead of Colt and Remington from the beginning of the war, it wouldn't have hurt their performance any, I'd wager. The R&S, as far as design and performance goes, rates comparison with the best.