I'm a firm believer in aperture sights - I just can't see a v-notch or u-notch or buckhorn rear sight. Even the fiber optic ones give me fits.
I recently built my own aperture sight for a .58 Zouave in such a way that I can re-install the original rear sight any time I want. Take a look at
http://www.huntingnet.com/forum/tm.aspx?m=2431005&mpage=1&key=&#243103 1
After using this homemade sight, I won't even consider going back to a notch type rear sight. I have a new .54 Great Plains flint lock that I haven't shot yet. I'm in the process of modifying the adjustable factory rear sight to something like the one I made for the Zouave (however, it will be much sleeker and will take advantage of the adjustable feature of the factory sight). The first range session will be with a peep.