Remington 1858 conversion?

[Mr. 16 gauge]

The movie 'pale rider' has been showing on one of the movie channels this month.....I was watching and I'm somewhat interested in the 1858 coversion unit that Clint Eastwood's character uses in the film.
I did a little research and found that there are units like that being made today, and they fit my current model 1858.

Has anybody here used one? I'm kinda curious as to the accuracy, efficacy, ect of these units. There kinda expensive ($250 or so), and that kind of coin will get me a 1860 Army reproduction (another pistol I've had a hankerin' for).

Any experiences would be appreciated.....thanks in advance.